Biased, because there is only survey of one group of people (one grade, one class). The sample (the class) is too small compared to the population (assuming it’s an average school size). You will end up with less than 1 percent of the population size thus the survey is not reliable information.
You would most likely use lettuce leaves, because grapes are little orbs of fruit with no leaves, zuchini are funny shaped veggies, and hibiscus is a type of tree. So, the most logical answer would be lettuce leaves.
The answer to that question is the sum of the hours he studied for on both days, which will be 1/4 + 3/8.
However, we cannot add fractions with different denominators. In this case, it's 4 and 8.
So if we want to add them, we must make the denominators similar to each other. How to make 4 into 8? We multiply it by 2: 4 x 2 = 8.
BUT when we multiply fractions, we must multiply both the numerator and the denominator by the same number to keep its original value. In this case, if you want to multiply 4 by 2, you must also multiply 1 by 2.
=> SO to make 1/4 into y/8, we will multiply it like this (1 x 2) / (4 x 2) = 2/8
Now we can add the 2 fractions together. 2/8 + 3/8 = (2 + 3)/8 = 5/8. THIS IS YOUR ANSWER.
TL;DR: He studied 5/8 (or 0.625) hour altogether on both days.
C might be the correct answer try it :)