Problema Solution

Hat sizes are determined by measuring the circumference of one’s head in either inches or centimeters. Use ratio and proportion to complete the following table.

Hat size Head circumference Head circumference

(to nearest 1/5 inch) to nearest centimeter)

6 7/8 21 3/5 55

7 ¾ ? ?

Answer provided by our tutors

Probably easiest to use decimal ratios.

7 3/4 = 7.75

6 7/8 = 6.875

1st box:

[21 3/5 = 21.6]

Head circumference = 21.6 * 7.75 / 6.875 = 24.35 inch = 24 2/5 to nearest 1/5 inch

[24 2/5 = 24.4]

2nd box:

Head circumference = 55 * 7.75 / 6.875 = 62 cm

or 55 * 24.35 / 21.6 = 62 cm to nearest cm