Grade 7 · Statistics & probability

Sampling and inference practice

Sampling and inference is a grade 7 math skill aligned to Common Core standard 7.SP.A.2: use data from a random sample to draw inferences about a population with an unknown characteristic of interest. Below are 8 practice questions with answers and step-by-step explanations, drawn from the 15 sampling and inference problems our math games drill.

CCSS 7.SP.A.215 questions in the bank
Sample questions

Try 8 for free

Question 1easy

In a random sample of 40, 12 were red marbles. Estimate how many of 200 are red in the whole population.

Proportion =1240= \dfrac{12}{40}. Estimate =1240×200=60= \dfrac{12}{40} \times 200 = 60.

Question 2easy

In a random sample of 30, 9 were left-handed students. Estimate how many of 300 are left-handed in the whole population.

Proportion =930= \dfrac{9}{30}. Estimate =930×300=90= \dfrac{9}{30} \times 300 = 90.

Question 3easy

In a random sample of 50, 15 were defective bulbs. Estimate how many of 400 are defective in the whole population.

Proportion =1550= \dfrac{15}{50}. Estimate =1550×400=120= \dfrac{15}{50} \times 400 = 120.

Question 4easy

In a random sample of 20, 7 were voters favoring the plan. Estimate how many of 100 are favoring in the whole population.

Proportion =720= \dfrac{7}{20}. Estimate =720×100=35= \dfrac{7}{20} \times 100 = 35.

Question 5easy

A random sample of 12 contained 3 successes. What is the sample proportion (as a simplified fraction)?

Proportion =312=14= \dfrac{3}{12} = \dfrac{1}{4}.

Question 6easy

A random sample of 20 contained 5 successes. What is the sample proportion (as a simplified fraction)?

Proportion =520=14= \dfrac{5}{20} = \dfrac{1}{4}.

Question 7easy

A random sample of 32 contained 8 successes. What is the sample proportion (as a simplified fraction)?

Proportion =832=14= \dfrac{8}{32} = \dfrac{1}{4}.

Question 8easy

In a random sample, 12 of 48 shoppers chose vanilla. What percent of all shoppers would you expect to choose vanilla?

1248=14=25%\dfrac{12}{48} = \dfrac{1}{4} = 25\%.

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Math games for Grade 7

Questions like these are served inside our head-to-head math games.

Blaster Gate gameBlaster GateBlast through the wall. First to clear wins.Blitz Tanks gameBlitz TanksSolve math to load shells. Out-think the battalion. Last math standing wins.
Tests that cover sampling and inference:
SBACNAEPACT AspireNC EOG/EOCVTCAP
More Grade 7 skills:
Simple interestProbability of simple eventsRatios, rates, and proportionsTwo-event compound probability word problemsProbability basicsRatio, rate, and proportion word problemsTwo-event conditional probability word problemsVolume of prisms and cylindersAll Grade 7 practice →

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