13. Here is a square.
Area
64 cm
The area of the square is 64 cm?
(a) Work out the length of one side of the square.

8

Step-by-step explanation:

√(64)

One side of the square is 8 cm

Given:

howler monkey: {15, 16, 17, 17, 17, 17, 18, 19}
spider monkey: {12, 13, 13, 14, 14, 14, 16, 16}

The mean of the first set (howler monkey) = (15 + 16 + 17 + 17 + 17 +17 + 18 + 19)/ 8 
The sum of all weights is divided by the number of monkeys weighed (n = 8)

mean = 17

Do the same for the second set (spider monkey) = 12+ 13 + 13+ 14 + 14+ 14 +14 +16 + 16 / 8

mean = 15.75

The ratio of the two is 17:15.75 or 1.08 is to 1.