In a representative survey 9 out of 12 middle schoolers prefer

doughnuts to candy bars. How many doughnuts would you predict you

need for a group of 250 middle schoolers? How many candy bars?

250/12=20.83

so there is about 21 times more people

20.8333 x 9 = 187.5

250-187.5=62.5

(I am going to put 62 so when you add up it will be 250 instead of 251)

about 188 people will have donuts and about 62 candy bars

187.5 doughnuts (about 188)

62.5 candy bars (about 63)

Step-by-step explanation:

So the proportion of middle schoolers who prefer doughnuts is p = 9/12. That means the proportion of middle schoolers who prefer candy is 1 - 9/12 = 3/12.

The number of middle schoolers is n = 250.

Let X represent the number of doughnuts you need. The expected number is E (X) = np, so multiply them together:

E (X) = np

E (X) = 250 * 9/12 = 187.5 doughnuts

Let Y represent the number of candy bars you need. The expected number is E (Y) = np, so multiply them together:

E (Y) = np

E (Y) = 250 * 3/12 = 62.5 candy bars