The mean of the test is 143 and the standard deviation is 15.7. if the scores have a bell-shaped distribution, what percentage of the scores are between 111.6 and 174.4?

If you're allowed to use a calculator here, use it!

This is basic normal probability, with mean 143 and s. d. 15.7.

I typed in the following:

normal cdf(111.6, 174.4, 143, 15.7) and got the probability 0.954.  In words, more than 95% of scores were between 111.6 and 174.4 on this test.

Rounding decimals is very similar to rounding other numbers. if the hundredths and thousandths places of a decimal is forty-nine or less, they are dropped and the tenths place does not change. for example, rounding 0.843 to the nearest tenth would give 0.8. , your welcome !