Question

You have a normal population scores with a mean of 25 and standard deviation of 6. what is the value that separates the top 25% of scores?

Answer 1

Given that,

mean = = 25

standard deviation = =6

Using standard normal table,

P(Z > z) = 25%

= 1 - P(Z < z) = 0.25

= P(Z < z ) = 1 - 0.25

= P(Z < z ) = 0.75

= P(Z <0.67 ) = 0.75  

z =0.67 (using standard normal (Z) table )

Using z-score formula  

x = z * +

x= 0.67 *6+25

x= 29.02

x=29