Question

The mean household income of Russian is approximately 25,500 euros. Suppose the household income in Russia is approximately normal. Find the standard deviation of household income such that 92% of the household income of Russian who make at least 15,000 euros? (no excel work)

Answer 1

Solution:-

Given that,

mean = = 25500

x = 15000

Using standard normal table,

P(Z > z) = 92%

= 1 - P(Z < z) = 0.92  

= P(Z < z) = 1 - 0.92

= P(Z < z ) = 0.08

= P(Z < -1.41 ) = 0.08  

z = -1.41

Using z-score formula,

x = z * +

15000 = -1.41 * + 25500

= 15000 - 25500 / -1.41

= 7447