In: Statistics and Probability
The SAT scores for students are normally distributed with a mean of 1000 and a standard deviation of 200. What is the probability that a sample of 45 students will have an average score between 970 and 1010? Round your answer to 3 decimal places.
Solution :
Given that ,
mean = = 1000
standard deviation = = 200
n = 45
= 1000
= / n= 200/ 45=29.81
P(970< < 1010) = P[(970-1000) / 29.81< ( - ) / < (1010-1000) / 29.81)]
= P( -1.01< Z <0.34 )
= P(Z < 0.34) - P(Z <-1.01 )
Using z table
=0.6331-0.1562
=0.4769
probability=0.477