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 of a 2 inch marble
Let's assume the cost of a 2 inch marble is x cents.
Since the 1 inch diameter marbles cost 30 cents less than the 2 inch marbles, the cost of a 1 inch marble is x - 30 cents.
Rochelle buys 25 1 inch marbles for her science project, so she spends 25 * (x - 30) cents on 1 inch marbles.
We know that Rochelle spends exactly 10 cents, so 25 * (x - 30) = 10.
Dividing both sides of the equation by 25, we get x - 30 = 10/25.
Simplifying the equation, we get x - 30 = 0.4.
Adding 30 to both sides of the equation, we get x = 0.4 + 30 = 30.4.
Therefore, the cost of a 2 inch marble is 30.4 cents.