GED Mathematical Reasoning Preparation Course：Data, statistics and probability

1. 第1题，共16题

   What is the mean of 3, 9, 5, 12 and 6?

   • A35
   • B6
   • C7
   • D9
   显示答案

   答案: C. 7

   Mean = sum ÷ count = 35 ÷ 5 = 7. The median is 6 and the range is 9.

2. 第2题，共16题

   What is the median of 12, 7, 15, 9, 20 and 11?

   • A12
   • B13
   • Cabout 12.33
   • D11.5
   显示答案

   答案: D. 11.5

   Put them in order: 7, 9, 11, 12, 15, 20. With an even count, the median is the mean of the two middle numbers: (11 + 12) ÷ 2 = 11.5.

3. 第3题，共16题

   A store sold shoes in these sizes: 8, 9, 9, 10, 7, 9, 8. What is the mode?

   • A8.57
   • B3
   • C9
   • D8
   显示答案

   答案: C. 9

   The mode is the value that appears most often. Size 9 appears three times.

4. 第4题，共16题

   Jon's mean score on 5 tests is 84. His first four scores are 80, 90, 78 and 85. What was his fifth score?

   • A84
   • B89
   • C83.25
   • D87
   显示答案

   答案: D. 87

   The 5 scores must add to 84 × 5 = 420. The first four add to 333, so the fifth is 420 − 333 = 87.

5. 第5题，共16题

   Ana works 3 hours at $16 an hour and 5 hours at $20 an hour. What is her average pay per hour for the 8 hours?

   • A$18.00
   • B$18.50
   • C$19.00
   • D$18.75
   显示答案

   答案: B. $18.50

   This is a weighted average: (3 × $16 + 5 × $20) ÷ 8 = ($48 + $100) ÷ 8 = $18.50. Simply averaging $16 and $20 ignores the hours.

6. 第6题，共16题

   The table shows a shop's sales. Between which two months did sales increase the most?

   Month	Sales
   January	120
   February	135
   March	128
   April	150
   May	162

   • AFebruary to March
   • BApril to May
   • CMarch to April
   • DJanuary to February
   显示答案

   答案: C. March to April

   The changes are +15, −7, +22 and +12. The largest increase, 22, is from March to April.

7. 第7题，共16题

   A family's monthly take-home pay is $3,200. The table shows how a circle graph splits the budget. How much goes to food?

   Budget item	Share
   Rent	35%
   Food	20%
   Transportation	15%
   Savings	10%
   Other	20%

   • A$1,120
   • B$480
   • C$640
   • D$20
   显示答案

   答案: C. $640

   Food is 20% of the budget: $3,200 × 0.20 = $640.

8. 第8题，共16题

   A scatter plot shows that students who study more hours tend to get higher test scores. How is this relationship described?

   • AA constant relationship
   • BA positive association
   • CNo association
   • DA negative association
   显示答案

   答案: B. A positive association

   When one value tends to go up as the other goes up, the points rise from left to right. That is a positive association.

9. 第9题，共16题

   A box plot of delivery times (in minutes) shows: minimum 12, first quartile 18, median 25, third quartile 31, maximum 40. What is the interquartile range?

   • A6 minutes
   • B13 minutes
   • C25 minutes
   • D28 minutes
   显示答案

   答案: B. 13 minutes

   Interquartile range = third quartile − first quartile = 31 − 18 = 13 minutes. 28 is the full range.

10. 第10题，共16题

    A bag has 4 red, 6 blue and 5 green marbles. You pick one without looking. What is the probability it is blue?

    • A2/3
    • B2/5
    • C1/6
    • D3/5
    显示答案

    答案: B. 2/5

    Probability = favorable ÷ total = 6 ÷ 15 = 2/5.

11. 第11题，共16题

    You flip a coin and roll a number cube (1 to 6). What is the probability of heads and a 6?

    • A1/12
    • B1/8
    • C7/12
    • D2/3
    显示答案

    答案: A. 1/12

    The events are independent, so multiply: 1/2 × 1/6 = 1/12.

12. 第12题，共16题

    You roll one number cube (1 to 6). What is the probability of rolling a 1 or a 6?

    • A1/6
    • B1/36
    • C1/3
    • D1/2
    显示答案

    答案: C. 1/3

    The two results cannot happen at the same time, so add: 1/6 + 1/6 = 2/6 = 1/3.

13. 第13题，共16题

    A box holds 4 red pens and 6 black pens. You take one pen, keep it, and take another. What is the probability both are red?

    • A2/15
    • B7/19
    • C4/25
    • D2/5
    显示答案

    答案: A. 2/15

    Without replacement, the second pick has one fewer red and one fewer pen: 4/10 × 3/9 = 12/90 = 2/15.

14. 第14题，共16题

    You have 4 shirts, 3 pairs of pants and 2 pairs of shoes. How many different outfits of one shirt, one pair of pants and one pair of shoes can you make?

    • A24
    • B9
    • C48
    • D12
    显示答案

    答案: A. 24

    Use the counting principle: multiply the choices. 4 × 3 × 2 = 24 outfits.

15. 第15题，共16题

    A club of 5 people chooses a president, a vice president and a secretary. No one can hold two jobs. How many ways can this be done?

    • A60
    • B125
    • C10
    • D15
    显示答案

    答案: A. 60

    Order matters, so this is a permutation: 5 × 4 × 3 = 60.

16. 第16题，共16题

    A pizza shop offers 6 toppings. How many ways can you choose 2 different toppings?

    • A36
    • B12
    • C30
    • D15
    显示答案

    答案: D. 15

    Order does not matter, so this is a combination: (6 × 5) ÷ (2 × 1) = 15.

键盘：按1–4作答，按 Enter 进入下一题。

真实考试：145 on each GED subject