The answer is B. You add all the numbers together and divide by the amount of numbers you have to find the mean. The missing height is 62 because 54+57+59+63+66+68+70+58=563
563/9 (amount of numbers you have including the missing height) = 63
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First, turn the fractions into mixed numbers.
21/4 - 27/8
Then. make the denominators the same.
4 * 2 = 8
21 * 2 = 42
42/8 - 27/8
42 - 27 = 15
15/8
15/8 = 1 7/8
