Question

Write an equation of variation to represent the situation and solve for the indicated information A bottle of 150 vitamins costs $5.25. If the cost varies directly with the number ofvitamins in the bottle, what should a bottle with 250 vitamins cost?Wei received $55.35 in interest on the $1230 in her credit union account. If the interestvaries directly with the amount deposited, how much would Wei receive for the sameamount of time if she had $2000 in the account?

Answer 1

A bottle of 150 vitamins costs $5.25.

The cost varies directly with the number of vitamins in the bottle.

What should a bottle with 250 vitamins cost?

Let C denotes cost and V denotes the number of vitamins.

The direct variation equation is

`C=kV`

Let us first find the value of k (constant of proportionality)

`k=(C)/(V)=(5.25)/(150)=0.035`

Now the cost of 250 vitamins may be found as

`\begin{gathered} C=kV \\ C=0.035*250 \\ C=\$8.75 \end{gathered}`

Therefore, the cost of 250 vitamins is $8.75.