Grace starts with 100 milligrams of a radioactive substance. The amount of the

substance decreases by each week for a number of weeks, w. She writes the

expression 100 (-) w to find the amount of radioactive substance remaining after w

weeks.

Ryan starts with 1 milligram of a radioactive substance. The amount of the substance

decreases by 40% each week for a number of weeks, w. He writes the expression (1 -

0.4) " to find the amount of radioactive substance remaining after w weeks.

Use the drop-down menus to explain what each part of Grace's and Ryan's

expressions mean.

Question

Mathematics

Rudy Mcgee

20 March, 19:54

Grace starts with 100 milligrams of a radioactive substance. The amount of the

substance decreases by each week for a number of weeks, w. She writes the

expression 100 (-) w to find the amount of radioactive substance remaining after w

weeks.

Ryan starts with 1 milligram of a radioactive substance. The amount of the substance

decreases by 40% each week for a number of weeks, w. He writes the expression (1 -

0.4) " to find the amount of radioactive substance remaining after w weeks.

Use the drop-down menus to explain what each part of Grace's and Ryan's

expressions mean.

+4

Answers (2)

Know the Answer?

William Oliver · Answer 1

100 = Initial Amount

1/4 = decay factor for each week

w = number of weeks

1/4w = decay factor after w weeks

1 - 0.4 = decay factor for each week

w = number of weeks

0.4 = percent decrease

Angie Chambers · Answer 2

100 is grace's initial amount. w is how much of the substance is being decrased each week. in ryan's equation, 1 is 100% of the substance, so the initial amount, and 0.4 is the amount that is being decreased.