Final answer:
To determine the number of index cards in a 3/4-inch tall stack, with each card being 3/160 of an inch thick, you divide the total stack height by the thickness of one card, resulting in 40 index cards.
Step-by-step explanation:
To find out how many index cards are in the stack, we will divide the total height of the stack by the thickness of one index card. Given that the stack's height is 3/4 of an inch tall and each index card is 3/160 of an inch thick, we can set up a division equation:
Number of cards = Total stack height / Thickness of one card
Therefore:
Number of cards = (3/4) / (3/160)
First, we convert the mixed fraction to an improper fraction: (3/4) = (3*160)/(4*160) = 120/160.
Now, we divide the fractions:
Number of cards = (120/160) / (3/160) = 120 / 3 = 40 index cards.
So, there are 40 index cards in the stack.