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

Question

$0.70

$0.10

$2.80

$2.50

Answer 1

Let the cost of the 2-inch marbles be \( x \) cents. Then the cost of the 1-inch marbles is \( x - 30 \) cents.

Rochelle buys 25 1-inch marbles, and the total cost for these marbles is given as $10, which equals 1000 cents. Therefore, we can set up the following equation:

\[ 25(x - 30) = 1000 \]

Now, distribute the 25:

\[ 25x - 750 = 1000 \]

Next, add 750 to both sides:

\[ 25x = 1750 \]

Now, divide by 25:

\[ x = 70 \]

Thus, the cost of a 2-inch marble is 70 cents, or \( \boxed{0.70} \).