Answer:
Hi your question is incomplete attached below is the complete question
answer : p ( X < 725 ) = 0.0116
Step-by-step explanation:
Given data:
Average life of bulbs (μ ) = 750 hours
standard deviation (б ) = 55 hours
n ( sample size ) = 25
X = 725
<u>Probability that the mean life of a random sample of 25 bulbs will be less than725 hours </u>
p ( X < 725 ) = p (( X - μ )/ б √n < 725 - 750 / 55√25 )
= P ( Z > - 2.27 )
Hence P ( X < 725 ) = 0.0116 ( using Z-table )
