Question

It's one of assignment questions and I can't post the whole question as it doesn't allow me but is naming the ink colors of the color words.

What is the probability that the average time to read 60 colour rectangles for males will be above 21 seconds? obtain the relevant mean’s and standard deviations from your calculator.

  

Answer 1

Assume
mean =24
standard deviation =12
the PDF of normal distribution is = 1/σ * √2π * e ^ -(x-u)^2/ 2σ^2
standard normal distribution is a normal distribution with a,
mean of 0,
standard deviation of 1
equation of the normal curve is ( Z )= x - u / sd/sqrt(n) ~ N(0,1)
mean of the sampling distribution ( x ) = 24
standard Deviation ( sd )= 12/ Sqrt ( 60 ) =1.5492
sample size (n) = 60

the probability that the average time to read 60 colour rectangles
for males will be above 21 seconds
P(X > 21) = (21-24)/12/ Sqrt ( 60 )
= -3/1.549= -1.9365
= P ( Z >-1.9365) From Standard Normal Table
= 0.9736