Deck 3: Decimal Fractions

Question 1

Carry the answer to three decimal places. A set of 2-inch-wide by -inch-thick carbon brushes fits the brush holders too tightly. It is necessary to take inch off the width and 0.015 inch off the thickness by sanding. Give in decimal form the thickness dimension of the carbon brushes after sanding.

Answer 1

.610

Question 2

Carry the answer to three decimal places. A set of 2-inch-wide by -inch-thick carbon brushes fits the brush holders too tightly. It is necessary to take inch off the width and 0.015 inch off the thickness by sanding. Give in decimal form the width dimension of the carbon brushes after sanding.

Answer 2

1.995

Question 3

Carry the answer to three decimal places. What is the total thickness of these shims taken from a bearing: 0.007 inch, 0.125 inch, 0.140 inch, 0.187 inch, and 0.004 inch?

Answer 3

.463

Question 4

Carry the answer to three decimal places. The cold resistance of an armature measures 0.096 ohm. After running for 5 hours, the resistance is 1.25 ohms. What is the difference in the resistance?

Question 5

Carry the answer to two decimal places. A contractor requires the following for a job: BX cable, $32.65; conduit pipe, $12.56; toggle switches, $24.45; and octal boxes, $7.50. What is the total cost?

Question 6

Carry the answer to three decimal places. Standard 1-inch conduit has an inside diameter of 1.575 inches and an outside diameter of 1.825 inches. Find the thickness of the wall.

Question 7

Carry the answer to three decimal places. The dry cells shown add up to a total voltage of 27.5 volts. What is the average number of volts for each dry cell?

Question 8

Carry the answer to two decimal places. The values of pieces of electrical equipment are as follows: one 0-150 voltmeter costing $45.50; one 0-10-kilowatt meter costing $165.50; one 0-30 ammeter costing $35.20; one 0-300 voltmeter costing $42.75; one 0-200 millivoltmeter costing $65.38; one 50-ampere shunt costing $9.85; and three 0-5 ammeters costing $45.60 each. Find the total value of these pieces.

Question 9

Carry the answer to three decimal places. The weight of a spool of wire is 27.11 pounds. The spool weighs 3.2 pounds. Find the cost of the wire per pound if the cost of the spool of wire is $74.44. Express the answer to the nearer tenth of a cent.

Question 10

The thickness of insulation between the copper conductor and the iron core of a motor armature are 0.002 inch of enameled insulation, 0.006 inch of cotton insulation, 0.010 inch of slot insulation, and 0.008 inch of varnished cambric insulation. Find the total thickness of insulation.

Question 11

Carry the answer to two decimal places. What is the cost of 1,250 feet of cable at $23.25 per one hundred feet?

Question 12

When the number 0.67 is entered into a calculator, it is necessary to enter the zero to the left of the number into the calculator.

Question 13

Carry the answer to three decimal places. A power company charges a city $1.2167 per street lamp per month. There are 1,125 street lamps supplied with current. What is the city's power bill per year for the street lamps?

Question 14

Carry the answer to three decimal places. The field current of a motor is 1.12 amperes at no load. However, when the full load is applied, the current increases to 1.87 amperes. What is the difference in amperes from no load to full load?

Question 15

Carry the answer to three decimal places. If W=3.000 inches, Y=1.750 inches, and Z=0.875 inch, find X.

Question 16

Carry the answer to two decimal places. Find the total weight of a 52-gallon steel drum and its contents if it contains 52 gallons of varnish weighing 8.16 pounds per gallon. The drum alone weighs 37.5 pounds.

Question 17

Carry the answer to two decimal places. What is the tax bill for a contractor if his shop has an assessed valuation of $35,000, and the tax rate is $27.50 per thousand dollars of assessed valuation?

Question 18

Carry the answer to two decimal places. The voltage at the terminals A and B in the diagram of the electric generator shown is 219.7 volts, and the voltage drop (loss in the line) is 3.96 volts. What is the voltage at the end of the line at points C and D?

Question 19

When entering a decimal number in a calculator, the whole number to the left of the decimal must be entered first.

Question 20

Carry the answer to three decimal places. The total current (amperes) is equal to the sum of the individual currents. Find the total current in the figure shown.

Question 21

Carry the answer to two decimal places. A certain type of cable weighs 500.88 pounds per one thousand feet. Determine the weight of 53 feet of this cable. Round the answer to the nearest hundredth.

Question 22

Carry the answer to two decimal places. What is the total cost to repair an electric outlet if the following materials and labor are required: one shallow box at $0.65, one ; -inch hickey at $0.98, one flush toggle switch at $1.17, and one hour of labor at $65?

Question 23

Carry the answer to two decimal places. The circumference of a pulley equals the diameter multiplied by 3.1416. Find the difference in circumference between the two pulleys shown.

Question 24

Carry the answer to four decimal places. A shim is made 0.0025 inch thick. The thickness should be 0.00225 inch. Find the difference in the thickness.

Question 25

Carry the answer to four decimal places. If A= 0.375 inch, B=0.923 inch, C=1.0992 inches, find G

Question 26

Carry the answer to four decimal places. If D=3.1875 inches and E=0.5625 inch, find C.

Question 27

Carry the answer to four decimal places. What is the difference in diameters between 13 wire and number 15 wire?

Question 28

Carry the answer to four decimal places. The inside diameter of a motor shaft bearing is 0.0075 centimeter wider than the shaft. The shaft diameter is 4.75 centimeters. What is the inside diameter of the bearing?

Question 29

Carry the answer to four decimal places. If one cubic inch of copper weighs 0.314 pound, find the weight of a piece of copper that contains 2.25 cubic inches.

Question 30

Carry the answer to two decimal places. A piece of -inch diameter copper rod is rolled down in a mill to 0.010 inch in thickness for magnet wire sleeving and clips. In decimal form, how much is the copper reduced in size?

Question 31

Carry the answer to two decimal places. The weight of a certain wire is 145 pounds per one thousand feet. What is the cost of 600 feet of this wire at $1.40 per one hundred pounds?

Question 32

Carry the answer to four decimal places. How much larger is the diameter of number 11 wire than that of number 16 wire?

Question 33

Carry the answer to four decimal places. A special resistance wire has a diameter of 0.037 inch. The next smaller size is 0.0345 inch in diameter. Find the difference in the diameters.

Question 34

Carry the answer to two decimal places. An electrician receives $787.50 for a 35-hour week. What is his rate of pay per hour?

Question 35

Carry the answer to four decimal places. The total current in the diagram divides at point A. How much current exists at point B?

Question 36

Carry the answer to two decimal places. What is the total weight of a container of 7 gallons of liquid insulating material if one gallon weighs 9.36 pounds and the container alone weighs 6.87 pounds?

Question 37

Carry the answer to two decimal places. The lamps in the figure require a total current of 7.76 amperes. How many amperes will 2 lamps require? (All the lamps are of the same type, and each requires the same number of amperes.)

Question 38

Carry the answer to four decimal places. If A= 0.3125 inch, B= 0.500 inch, and C=1.062 inches Find D.

Question 39

Carry the answer to two decimal places. Six hundred twenty-five watertight screw connectors are purchased for $0.1725 each. Find the total cost.

Question 40

Carry the answer to two decimal places. What is the total thickness of insulation between the copper conductor and the iron core of a motor armature if there is 0.003 inch of enameled insulation, 0.065 inch of cotton insulation, 0.015 inch of slot insulation, and 0.007 inch of varnished cambric insulation?

Question 41

Carry the answer to five decimal places. A meter is to be bolted to a switchboard. The meter studs that will fit into the holes on the switchboard are 0.4365 inch in diameter. Express the hole sizes in decimal form if they are to be inch larger in diameter than the studs.

Question 42

Mixed number format: 10 (Use a space between the whole number and the numerator.) Simple fraction: Reduce to lowest form. A piece of 0.0625-inch-thick copper is used to make a sleeve for a joint. What is the thickness of this material expressed as a fractional part of an inch?

Question 43

What is the resistance of a piece of copper wire that has a size of 2.5 mil-feet if 1 mil-foot has a resistance of 10.4 ohms?

Question 44

Carry the answer to four decimal places. If X = 0.9875 inch and Y = 0.675 inch, find W.

Question 45

Carry the answer to four decimal places. A bearing with an inside diameter of 1 inches is found to be 0.008 inch oversize for the armature shaft. What should the diameter of the bearing be to fit the shaft? Allow 0.002-inch clearance for lubrication.

Question 46

The electrician uses the following amounts of 1-inch EMT conduit: 22.5 feet, 8 feet, 30.25 feet, and 816.75 feet. Find the total amount of EMT used.

Question 47

Carry the answer to five decimal places. A carbon brush measures inch thick and inches wide. It is to have a copper plating on all sides 0.015 inch thick. What will be the finished width in decimal form of the brush with the copper plating?

Question 48

Carry the answer to five decimal places. Express the diameter of a -inch twist drill as a decimal.

Question 49

Carry the answer to four decimal places. If A = 0.305 inch, C = 1.0425 inches, and D = 3.860 inches, find B.

Question 50

Carry the answer to four decimal places. If B = 0.500 inch and G = 2.0222 inches, find C.

Question 51

Using a calculator, what is the sum of 3.5 + 4.72 + 5.56 + 0.234?

Question 52

Carry the answer to four decimal places. The actual inside diameter (10) of a 3-inch conduit is 3.375 inches, and the actual outside diameter (00) is 3.9375 inches. What is the wall thickness of this conduit?

Question 53

Carry the answer to five decimal places. A carbon brush measures inch thick and inches wide. It is to have a copper plating on all sides 0.015 inch thick. What will be the finished thickness in decimal form of the brush with the copper plating?

Question 54

A contractor pays an electrician $910 per week and a helper $560 per week. If the work week consists of 35 hours, find the cost per hour for labor on a job using two electricians and two helpers.

Question 55

Carry the answer to four decimal places. Determine the circumference (C) of a grinding wheel if the diameter (d) is 12 inches. Use the following formula: C = d where = 3.1416

Question 56

Carry the answer to four decimal places. The lighting set shown has the same number of volts across each lamp. The sum of all lamp voltages is equal to the total number of volts. Find the number of volts across each lamp.