In a study conducted in 1980, researchers calculated the height difference between couples with kids in the UK. They found that the height difference between husband and wife follows a normal distribution with mean 5.6 inches and standard deviation equal to 3.7 inches.

1) What is the difference in height for the middle 68% of the couples in the study?
2) Calculate the percentage of couples in which the man is 5 inches taller than the woman. (you have to use Table B in the book)
3) (harder) Calculate the percentage of couples that have about the same height. Assume that a couple has the same height when the height difference is less than one inch.