Testinar Grade 7 math

Making Inferences from Random Samples

Students will build Grade 7 mastery of making inferences from random samples using models, equations, and test-style reasoning.

CH08-02 Statistics
Name
Date
Score
____ / 8
Directions Solve each problem. Show your reasoning on the page or on separate paper. Check the answer key only after finishing.

  1. In a random sample of \(50\) students, \(18\) said they prefer science. About how many students in the whole school of \(800\) are likely to prefer science?

    1. \(180\)
    2. \(288\)
    3. \(324\)
    4. \(360\)

  2. In a random sample of \(120\) middle school students, \(45\) play a musical instrument. The school has \(840\) students. About how many are likely to play an instrument?

    1. \(270\)
    2. \(315\)
    3. \(420\)
    4. \(504\)

  3. In a sample of \(90\) items from a factory, \(27\) were defective. If the factory produces \(2700\) items per day, about how many are expected to be defective?

    1. \(300\)
    2. \(450\)
    3. \(810\)
    4. \(1080\)

  4. A health clinic surveyed \(150\) patients and found that \(42\) have high blood pressure. The clinic sees \(500\) patients per month. About how many have high blood pressure?

    1. \(84\)
    2. \(112\)
    3. \(140\)
    4. \(168\)

  5. In a sample of \(100\) apps on a phone, \(16\) are gaming apps. A mobile device company has \(8000\) app downloads tracked. About how many are gaming apps?

    1. \(800\)
    2. \(1000\)
    3. \(1280\)
    4. \(1600\)

  6. Three samples show proportions of \(\frac{15}{50}\), \(\frac{12}{40}\), and \(\frac{18}{72}\) of students who prefer science. Which two samples have the same proportion?

    1. First and second
    2. Second and third
    3. First and third
    4. None have the same proportion

  7. A survey of \(70\) people found \(28\) prefer hiking. Which estimate of the total population preferring hiking is most reasonable if the population is \(3500\)?

    1. \(980\)
    2. \(1200\)
    3. \(1400\)
    4. \(1500\)

  8. A random sample of \(125\) vehicles found \(50\) were electric cars. The city has \(5000\) registered vehicles. How many are estimated to be electric?

    1. \(2000\)
    2. \(2500\)
    3. \(3125\)
    4. \(3750\)
Teacher and parent reference

Answer key and explanations

  1. B. \(288\)

    Set up the proportion: \(\frac{18}{50}=\frac{x}{800}\). Solve: \(x=\frac{18\times800}{50}=288\).

  2. B. \(315\)

    \(\frac{45}{120}=\frac{x}{840}\). Reduce to \(\frac{3}{8}=\frac{x}{840} \Rightarrow x = 315\).

  3. C. \(810\)

    \(\frac{27}{90}=\frac{x}{2700}\). Reduce to \(\frac{3}{10} \Rightarrow x = 810\).

  4. C. \(140\)

    \(\frac{42}{150}=\frac{x}{500}\). Simplify: \(\frac{7}{25}=\frac{x}{500} \Rightarrow x = 140\).

  5. C. \(1280\)

    \(\frac{16}{100}=\frac{x}{8000}\). So \(x = 0.16 \times 8000 = 1280\).

  6. A. First and second

    \(\frac{15}{50}=0.30\); \(\frac{12}{40}=0.30\); \(\frac{18}{72}=0.25\). First and second both equal \(30\%\).

  7. C. \(1400\)

    \(\frac{28}{70}=\frac{x}{3500}\). Reduce: \(\frac{2}{5}=\frac{x}{3500} \Rightarrow x = 1400\).

  8. A. \(2000\)

    \(\frac{50}{125}=\frac{x}{5000}\). Reduce: \(\frac{2}{5}=\frac{x}{5000} \Rightarrow x = 2000\).

Free Testinar sample Reviewed November 6, 2026 testinar.com
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