Half-Life Formula #12-13

Question

Assume that my lawn is encroaching my garden and reduces my space, on average, by 8% each year.

 Approximately how many years before the garden space has been cut in half?

(Round to the nearest tenth.)

 If the garden started out at 925 square feet, approximately how many square feet will there be in 10 years?

(Round to the nearest whole number.)

Answer 1

Using Rule of 70, Time for the lawn to be cut in half = 70 /8 = 8.75 yrs = 8.8 yrs( rounded to tenth)

 

Lawn garden reduces by continuous rate. Lawn in 10yrs =925 * .92¹⁰ =925 * .434 =401.8 sq. ft