Estimation Problems

Estimation questions require knowledge of the following topics: estimation of population parameters and margin of error, properties of point estimators, including unbiasedness and variability, logic of confidence intervals, meaning of confidence level and properties of confidence intervals, large sample confidence interval for a difference between two proportions, confidence interval for the slope of a least-squares regression line.

Examples of multiple choice questions with point estimators and confidence intervals:

1. The quality department of an electronics manufacturer randomly selected 100 resistors. The mean resistance of the resistors was 201.5Ω and the standard deviation was .4Ω. Find the 98% confidence interval for this problem.

a) 201.5+/-.093
b) 201.5+/-.231
c) 201.5+/-.120
d) 201.5+/-.333
e) 201.5+/-.250

2. A large sample of size n is used to estimate the confidence interval for a proportion p. After further evaluation, the standard deviation is considered too large. What size sample we need to use for a new standard deviation equal to one tenth of the original standard deviation?

a) 10·n
b) 50·n
c) 100·n
d) 141·n
e) 200·n