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)

$k=\frac{C}{V}=\frac{5.25}{150}=0.035$

Now the cost of 250 vitamins may be found as

$\begin{gathered} C=kV \\ C=0.035\times250 \\ C=\ 8.75 \end{gathered}$

Therefore, the cost of 250 vitamins is $8.75.