Question

The amount of money that Charlie saves each week is directly proportional to the amount he earns. Last week Charlie saved $32 on his earnings of $512. At the same rate, how much will Charlie save this week on his earnings?

Answer 1

Question

The amount of money that Charlie saves each week is directly proportional to the amount he earns. Last week Charlie saved $32 on his earnings of $512. At the same rate, how much will Charlie save this week on his earnings of $448?

Answer:

Charlie saved $ 28

Solution:

Given that amount of money that Charlie saves each week is directly proportional to the amount he earns

Let y represent of saved money and x represent amount of earned money

Therefore,

$\text{ Amount of money saved each week } \propto amount he earns$

$y \propto x$

y = kx --- eqn 1

Where "k" is the constant of proportionality

Last week Charlie saved $32 on his earnings of $512

y = 32 and x = 512

Substituting in eqn 1, we get

$32 = k(512)\\\\k = \frac{32}{512} = 0.0625$

To find amount of saved money, we will substitute k = 0.0625 and x = 448 in eqn 1

y = 0.0625(448) = 28

Thus charlie saved $ 28