The answer is 3.68, because in order to round to the nearest hundredth, we look to the digit to the right in the thousandths place. If that digit is less than or equal to 4, then all digits to the right are removed; however, if that digit is 5 or greater, then 1 is added to the digit in the hundredths place.
Therefore, in 3.6789, 7 is in the hundredths place and 8 is in the thousandths place. 8 is greater than 5, so we add 1 to 8, and 1+8 = 9.
