what sample size is needed to give a margin of error within +- 2.5% in estimating a population proportion with 90% confidence? We estimate that the population proportion is about 0.4.

answer by jkismyhusbandbae:

a) how close a measured value is to the actual (true) value.

  measure of length.   there are 12 inches in a foot, and 36 inches in a yard.   one inch is exactly 2.54 centimeters.

accuracy is how close something is to an actual answer but it is not exactly correct.