Question

Michael started a savings account with $100. After 6 weeks, he had $140, and after 12 weeks, he had $260. What is the rate of change of money in his savings account per week?

this question looks easy but nothing makes sense to me second half didn't line up with my answer

Answer 1

Rate of change of money in Michael's account will be $20 per week.

Explanation:

If we draw a graph for the duration of investment on x-axis and amount in the account on y-axis, ordered pairs for both the conditions will be,

After 6 weeks, amount in the account = $140

Ordered pair : (6, 140)

After 12 weeks, amount in the account = $260

Ordered pair : (12, 260)

Rate of change in hi account per week =
`(\triangle y)/(\triangle x)`

=
`(260-140)/(12-6)`

=
`(120)/(6)`

= $20 per week

Therefore, rate of change of money in Michael's account will be $20 per week.