Making Predictions with Random Samples Proportions

On a youth soccer team 3 out of the 12 team members have played in previous years. Based on this information, if 150 kids are in the youth soccer league, then how many could be expected to have played the year before?*NOTE: enter your answers as a number ONLY.

A principal randomly chooses 40 students from grade 5. Of these students, 9 were wearing watches. Based on this information, what is the most reasonable prediction of the number of students wearing watches in a group of 120 students?

• 27

• 9

• 18

• 80

At an assembly 7 out of 10 students who entered the gym were carrying a backpack. Based on this information, if 700 students were at the assembly, how many students could be expected to be carrying a backpack?

• 49

• 490

• 210

• 421

A poll was taken of Hobby Middle School, 25 out of 30 students said they would prefer pizza on Friday’s. Out of 1200 students, what is a reasonable prediction of how many students would prefer pizza on Fridays?

• 100

• 1000

• 10

• 1

• 10820
• 10920
• 11820
• 11920

In a survey, 45 out of a random sample of 150 people said they prefer tea over coffee. Predict how many people would prefer tea in a city of 30,000 people.

• 9000

• 15000

• 4500

• 12000

Answer explanation

Since 45 out of 150 prefer tea, the ratio is 45/150. Applying this ratio to 30,000 people gives 9000 people who would prefer tea.

A survey conducted on a random sample of 120 people in a town shows that 60 people own a pet. If the town has 4800 people, how many people in the town are likely to own a pet?

• 2400

• 1200

• 1800

• 3000

Answer explanation

Since 60 out of 120 people own a pet in the sample, we can estimate that 2400 out of 4800 people in the town likely own a pet (60/120 = 2400/4800). Therefore, the correct answer is 2400.

In a random sample of 200 seeds, 140 seeds germinated. Predict the number of seeds that would germinate if 1000 seeds were planted.

• 700

• 500

• 600

• 800

Answer explanation

To find the number of seeds that would germinate if 1000 seeds were planted, use the proportion method: (140 seeds germinated / 200 seeds) = (x seeds germinated / 1000 seeds). Solving for x gives 700 seeds germinated.

• 13
• 14
• 15
• 16

A random sample of 200 people at a concert shows that 120 people are wearing hats. Predict the number of people wearing hats if 800 people are at the concert.

• 480

• 320

• 600

• 400

Answer explanation

To predict the number of people wearing hats for 800 attendees, use the ratio of people wearing hats in the sample. 120/200 = x/800. Solving for x gives 480.