Marbles come in 2 sizes.One inch diameter and 2 inch diameter the one inch diameter marbles cost 30 cents less than the 2 inch marbles.Rochelle buys 25 1 inch marbels for her science project and spends exactly $10.Find the cost of a two inch marble

Question

A. 2.50
B. O.10
C. O.70
D. 2.80

Answer 1

Let the cost of a 2-inch marble be \( x \) dollars. Then, since the 1-inch marbles cost 30 cents less than the 2-inch marbles, the cost of a 1-inch marble would be \( x - 0.30 \) dollars.

Rochelle buys 25 one-inch marbles for a total of $10:

\[ 25(x - 0.30) = 10 \]

Now we can solve for \( x \):

1. Distribute the 25:

\[ 25x - 7.50 = 10 \]

2. Add 7.50 to both sides:

\[ 25x = 17.50 \]

3. Divide by 25:

\[ x = \frac{17.50}{25} = 0.70 \]

Thus, the cost of a 2-inch marble is \( \boxed{0.70} \).

So the answer is C. 0.70.