# 05exS - ISOM111 Business Statistics (Fall 2010) Solutions...

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

ISOM111 Business Statistics (Fall 2010) Solutions for Tutorial Exercise 5 1. Let X be the number of recovery days by new therapy and μ be its mean. (a) x =12 σ =3 n =70 As n =70 > 30 , by CLT, X N ( μ, σ 2 70 ) The 95% con f dence interval for the mean recovery days by new therapy is : x ± z 0 . 025 ( σ n )=12 ± 1 . 96( 3 70 )=(11 . 2972 , 12 . 7028) (b) x =12 σ =3 n =25 As we don’t know the distribution of X n =25 < 30 assume X N X N ( μ, σ 2 70 ) The 95% con f dence interval for the mean recovery days by new therapy is : x ± z 0 . 025 ( σ n )=12 ± 1 . 96( 3 25 )=(10 . 824 , 13 . 176) (c) B =0 . 5 B> n n> ( 2 . 576 3 0 . 5 ) 2 > 238 . 8879 Take z =2 . 576 ,n> 238 . 8879 n =239 Take z =2 . 575 ,n> 238 . 7025 n =239 Take z =2 . 58 ,n> 239 . 6304 n =240 (d) From part (b), B =1 . 176 B > n 1 . 176 > z 3 70 z 6 1 . 176 70 3 6 3 . 28 With z =3 . 28 ,con f dence level

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.

## This note was uploaded on 01/06/2011 for the course ISOM 111 taught by Professor Hu,inchi during the Fall '10 term at HKUST.

### Page1 / 3

05exS - ISOM111 Business Statistics (Fall 2010) Solutions...

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

View Full Document
Ask a homework question - tutors are online