To find the product of $1.15 and 10, Justin can simply multiply the number directly. However, if he wants to use the concept of moving the decimal point, he should know that multiplying by 10 shifts the decimal point one place to the right.
Therefore, the correct response is:
He knows that 10 is 10 to the power of 1, so he needs to move the decimal point in 1.15 one place to the right.