Question

Q Search this course Homework of 70 n ±8 of the population mean (to 4 decimals)? Check

Answer 1

Answer:

a).

standard error = sd/sqrt(n) = 70/sqrt(125) =6.2610

we have to find P( 292 <mean x < 308)

z value for 292, z =(292-300)/6.2610 = -1.28

z value for 308, z =(308-300)/6.2610 = 1.28

P( 292 <mean x < 308) = P( -1.28 <z<1.28)

=P( z < 1.28)-P( z < -1.28)

= 0.8997 - 0.1003

=0.7994

b).

we have to find P( 289 <mean x < 311)

z value for 289, z =(289-300)/6.2610 = -1.76

z value for 311, z =(311-300)/6.2610 = 1.76

P( 289 <mean x < 311) = P( -1.76 <z<1.76)

=P( z < 1.76)-P( z < -1.76)

= 0.9608-0.0392

=0.9216