The following stem-and-leaf diagram shows the speeds in miles per hour (mph)of 14 cars approaching a toll booth on a bridge in Oakland,California. How many of the cars were traveling faster than 25 mph but slower than 40 mph?
A) 8
B) 9
C) 10
D) 12

Question

The following stem-and-leaf diagram shows the speeds in miles per hour (mph)of 14 cars approaching a toll booth on a bridge in Oakland,California.  How many of the cars were traveling faster than 25 mph but slower than 40 mph?
A) 8 
B) 9 
C) 10 
D) 12

Quizplus · Accepted Answer

To find the number of cars traveling faster than 25mph but slower than 40mph, we need to look at the 2nd and 3rd digits of the numbers in the stem-and-leaf diagram. 
There are 5 cars with speeds between 20 and 29mph (20, 22, 23, 28, 29) and 3 cars with speeds between 30 and 39mph (30, 32, 36). Therefore, there are a total of 5 + 3 = 8 cars traveling faster than 25mph but slower than 40mph. 
The only answer choice that matches this is B) 9, which is incorrect. Therefore, the correct answer is B) 8.

The Following Stem-And-Leaf Diagram Shows the Speeds in Miles Per