UA · Unit 5 review

1. 1.

   Grace leaves a 15% tip on a $160 bill. How much is the tip?

   Answer. $24

   15% of 160 = 24.

2. 2.

   A price goes from $120 to $132. What is the percent increase?

   Answer. 10%

   Change = 12; divide by 120 → 10%.

3. 3.

   Is this sampling method random? A reporter asks only the first 8 fans at the front of a line.

   Answer. not random (convenience)

   not random (convenience)

4. 4.

   A population mean is unknown. Sample means from samples of size 25 tend to vary. Which sample size would you expect to give a sample mean closer to the population mean: 10 or 100?

   Answer. 100

   Larger random samples tend to have sample means closer to the population mean.

5. 5.

   Class A has median 18 and IQR 4. Class B has median 25 and IQR 4. Which class typically scored higher? Write a complete answer — Priya will compare with a partner.

   Answer. Class B

   Same spread (IQR 4), higher median in Class B (25 vs 18).

6. 6.

   Nora leaves a 25% tip on a $160 bill. How much is the tip? Then Theo needs 4 of that amount. What is the total they need?

   Answer. $160

   25% of 160 = 40. Then multiply by 4: $160.

7. 7.

   A price goes from $120 to $60. What is the percent decrease? Write a complete answer — Jonah will compare with a partner.

   Answer. 50%

   Change = 60; divide by 120 → 50%.

8. 8.

   Is this sampling method random? A reporter asks only the first 8 fans at the front of a line. Write a complete answer — Malik will compare with a partner.

   Answer. not random (convenience)

   not random (convenience)

9. 9.

   A population mean is unknown. Sample means from samples of size 25 tend to vary. Which sample size would you expect to give a sample mean closer to the population mean: 10 or 100? Then Owen needs 4 of that amount. What is the total they need?

   Answer. 400

   Larger random samples tend to have sample means closer to the population mean. Then multiply by 4: 400.

10. 10.

    Class A has median 16 and IQR 4. Class B has median 23 and IQR 4. Which class typically scored higher? Write a complete answer — Nora will compare with a partner.

    Answer. Class B

    Same spread (IQR 4), higher median in Class B (23 vs 16).

11. 11.

    Think

    Theo tried this problem:
    Ava leaves a 20% tip on a $120 bill. How much is the tip?
    Theo wrote $48. That is not correct. What is the right answer?

    Answer. $24

    Theo’s answer $48 is off. 20% of 120 = 24.

12. 12.

    Think

    Mei tried this problem:
    A price goes from $50 to $62.5. What is the percent increase?
    Mei wrote 50%. That is not correct. What is the right answer?

    Answer. 25%

    Mei’s answer 50% is off. Change = 12.5; divide by 50 → 25%.

Original extra practice. Keys are computed from the items, not guessed.