Please help me! Simplify each ratio. Write the simplified version in the same form of the ratio.

3 to 6
5:20
18 to 22
1820
2555
6 to 42
18 to 10
12 to 4
16:8
24 to 16
18 to 36
54 to 9
81:27
72 to 9
1812

The brain volumes (cm cubed) of 50 brains vary from a low of 904 cm cubed to a high of 1488 cm cubed. use the range rule of thumb to estimate the standard deviation s and compare the result to the exact standard deviation of 175.5 cm cubed, assuming the estimate is accurate if it is within 15 cm cubed