Question 1010388
Your ratio is 1.5:4. You can write it as a fraction: 1.5/4. And in a fraction, the BOTTOM NUMBER tells you the size of the whole "thing". Let's pretend for a moment that we are talking about a pizza. The pizza has been sliced into 8 pieces. I take one piece. How much of the pizza did I take? I took 1/8.
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Back to your problem. You want to know for 10 people:
10/4= 2.5. So 10 is 2.5 times more people than 4. And for every 4 you need 1.5 cups of flower and since you have 2.5 times more people you will need 2.5 times more flower:
2.5*1.5= 3.75 You need 3.75 cups of flower.
J