The Regional Center for Health Survey recently estimated that the mean weight for adult Indian women was 52 kg in 1968 and 65 kg in 2012.

(a) Suppose these estimates had a standard error of 1.2 kg each year. Estimate the increase in mean weight in the population from 1968 to 2012, and find and interpret the standard error of that estimate.

(b) Show that the estimated mean in 2012 was 1.25 times the estimated mean in 1968. Express this in terms of the percentage increase.

(c) The estimated mean weights for men were 71 kg in 1968 and 81 kg in 2012. Find and interpret the difference and the ratio.