# QUIZ 3-5 - Need x such that P( X > x ) = 0.10. Need z...

This preview shows pages 1–2. Sign up to view the full content.

STAT 400 Spring 2011 Version E Name _________________________ Quiz 3 (10 points) Be sure to show all your work, your partial credit might depend on it. No credit will be given without supporting work. 1. The heights of adult males in Neverland are normally distributed with mean of 69 inches and standard deviation of 5 inches. a) (4) What proportion of adult males are between 5 feet (60 in) and 6 feet (72 in) tall ? P( 60 < X < 72 ) = - < - < 5 69 72 5 69 60 P Z = P( 1.80 < Z < 0.60 ) = area between 1.80 and 0.60 = Φ ( 0.60 ) – Φ ( 1.80 ) = 0.7257 – 0.0359 = 0.6898 . b) (3) How tall must a male be to be among the tallest 10% of the population?

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Need x such that P( X > x ) = 0.10. Need z such that P( Z > z ) = 0.10. Φ ( z ) = 1 – 0.10 = 0.90. z = 1.28 . z x =-σ μ 28 . 1 5 69 =-x . x = 69 + 5 ⋅ 1.28 = 75.4 inches. A male must to be over 75.4 inches tall. c) (3) How "tall" must a male be to be among the shortest third of the population? Need x such that P( X < x ) = 0.3333. Need z such that P( Z < z ) = 0.3333. Φ ( z ) = 0.3333. z = – 0.43 . z x =-σ μ 43 . 5 69-=-x . x = 69 + 5 ⋅ ( – 0.43 ) = 66.85 inches. A male must to be under 66.85 inches "tall." If P( X < x ) = 0.33, then x = 69 + 5 ⋅ ( – 0.44 ) = 66.8 inches....
View Full Document

## This note was uploaded on 11/28/2011 for the course STAT 400 taught by Professor Kim during the Spring '08 term at University of Illinois, Urbana Champaign.

### Page1 / 2

QUIZ 3-5 - Need x such that P( X > x ) = 0.10. Need z...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online