The Precision Scientific Instrument Company manufactures thermometers that are supposed to give readings of 0°C at the freezing point of water. Tests on a large sample of these thermometers reveal that at the freezing point of water, some give readings below 0°C (denoted by negative numbers) and some give readings above 0°C (denoted by positive numbers). Assume that the mean reading is 0°C and the standard deviation of the readings is 1.00°C. Also assume that the frequency distribution of errors closely resembles the normal distribution. A thermometer is randomly selected and tested. Find the temperature reading corresponding to the given information.
-If 7% of the thermometers are rejected because they have readings that are too high, but all other thermometers are acceptable, find the temperature that separates the rejected thermometers from the others.
A)1.45°
B)1.26°
C)1.48°
D)1.39°

Question

Quizplus · Accepted Answer

The temperature that separates the top 7% of a normal distribution from the rest corresponds to the 93rd percentile. Using a standard normal distribution table or calculator, the z-score for the 93rd percentile is approximately 1.48.

The Precision Scientific Instrument Company Manufactures Thermometers That Are Supposed