Question
need help solving
Note: Answer the Question(s) by Using the T1-30XA (or other approved) Calculator. IMPORTANT: Make sure you carry all decimals until you reach your answer, then round to four decimals The Better Business Bureau settles 75% of complaints it receives involving new car dealers. Suppose a sample of 160 complaints involving new car dealers is selected. Find the probability that Better Business Bureau settles less than 133 of these complaints. (See exercise 35 on page 332 of your textbook for a similar problem.) Probability
Explanation / Answer
from normal approximation:
for mean =np=160*0.75=120
and std deviation =(np(1-p))1/2 =5.4772
therefore probability of less then 133 compaints =P(X<=132) =P(Z<(132.5-120)/5.4772) =P(Z<2.2822)
=0.9888
(note : from direct binomial distribution probability =0.9909)