Question

a purchasing manager at a university is investigating which brand of lcd projector to purchase for equipping classrooms. of major concern to her is the lifetime of the light bulbs used in the projectors. one company has published the following histogram regarding the lifetimes of a sample of 50 bulbs used in its lcd projectors. based on the histogram, find the proportion of bulb lifetimes in the sample that are less than 950 hours. write your answer as a decimal, and do not round your answer.

Explanation:

Step1: Find the number of bulbs with lifetime less than 950 hours

Add the frequencies of the intervals 700 - 750, 750 - 800, 800 - 850, 850 - 900 and 900 - 950. So, $5 + 6+16 + 11+8=46$.

Step2: Calculate the proportion

The total number of bulbs in the sample is 50. The proportion is $\frac{46}{50}$.

Answer:

0.92