1. The mean number of days leave taken by the lecturers for a year is 150 days, while the standard deviation is 14 days. If the error received is 2 days, how many of the lecturers who should be selected as samples in the 97 per cent confidence level?

2. Assume that the initial samples of 200 single unit calculator show that 9 per cent are not functioning properly. How many calculators to be selected by the company using 90 per cent level of confidence interval if the error will be within 0.02 of the proportion of the population?

Reference :

* Z & T -table distribution

https://drive.google.com/file/d/1F7WSECgudwiFAquk2unaZenUS84kBwBJ/view?usp=drivesdk

Confidence Interval for Confidence Interval for Mean Proportion Sample Size When n > 30 or o is known Infinite @ n/N 30 or o is known Finite @ n/N > 0.05 To find the sample size for proportion: Xtz- N -n 2 Jn VN-1 Z n = p(1- p) F T Distribution - when n