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?

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

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