Calculating height that decreases 0.06 cm per year

Question

When working on a report for class, Catrina read that a woman of the age of 40 can lose approximately 0.06 centimeters of height per year.

(a) Catrina's aunt Nancy is 40 years old and 5 feet 7 inches tall. Assuming her height decreases at this rate after the age of 40, about how tall will she be at age 65? Explain your reasoning. (Remember that 1 inch = 2.54 centimeters.)

(b) Catrina's 90­-year-­old grandmother is 5 feet 1 inch tall. Assuming her grandmother's height has also decreased at this rate, about how tall was she at age 40? Explain your reasoning.

Answer 1

(a) If Nancy is 5 ft 7 in (67 inches) tall at age 40 and gets shorter by 0.06 cm per year, then by age 65, she will have lost 25(0.06) = 1.5 cm of height. Convert this to inches: 1.5 cm = 1.5/2.54 in = .59 in. This means she will be about 67 - 0.59 = 66.41 inches tall at age 65.

 

(b) Instead of subtracting the loss in height, you would add it to her grandmother's height at age 90 (61 inches). Find the height loss in cm, convert to inches, and add it to 61 inches. This should give you the correct answer.