GIVEN:
We are given the mean and standard deviation for a sample size of 77 land and buildings per acre as follows;

Required;
(a) To estimate the number of farms whose land and building values per acre are between $1500 and $1700.
(b) If 21 additional farms were sampled, about how many of these additional farms would you expect to have land and building values between $1500 per acre and $1700 per acre?
Step-by-step solution;
The empirical rule states that for a bell shaped distribution, the deviation from the mean follows the pattern below;

Looking at the range given, we can determine the following;


We can now see that the data is 1 standard deviation from the mean (both at the upper limit and the lower limit).
Using the empirical rule as summarized above, we can safely say 68% of the sample size will lie between $1500 and $1700.
Therefore, we can calculate as follows;

This means,
(A) Approximately 52 farms will have their values between $1500 and $1700 per acre.
If the sample size were increased by 21 additional farms, that is;


Since we are concerned about the "additional 21,"

Therefore,
ANSWER:
(A) The number of farms whose land and building values per acre are between $1500 and $1700 is 52 (rounded to the nearest whole number)
(B) Additional farms you would expect to have land and building values between $1500 per acre and $1700 per acre is 31.