44 multiple-choice questions on Measures of Central Tendency from Mathematics, each with the correct answer and, where available, a teacher's explanation. Read through them to revise the chapter, then practise the same questions one by one to test yourself.
1. A data set has two values that occur most often. It is called:
bimodal
median
skewed
unimodal
Answer: A) bimodal
Explanation: Two modes — bimodal. SLO M-09-C-03 · Application
2. A government plans to spend 40% of a fund on schools (cost index 120), 35% on hospitals (index 150) and 25% on roads (index 100). The weighted mean cost index is:
3. Class Frequency ------ 20–25 2 25–30 9 30–35 14 35–40 11 40–45 4 (Classes are continuous: a –b means a le x < b.) Using Median = l + hf ( n2 - c ), the median is:
35
36.25
30
33.21
Answer: D) 33.21
Explanation: n = 40, n2 = 20. The median class is 30 –35 with l = 30, h = 5, f = 14, c = 11. Median = 30 + 514(20 - 11) = 33.21. SLO M-09-C-02 · Understanding
16. Class Frequency ------ 10–20 5 20–30 8 30–40 12 40–50 9 50–60 6 (Classes are continuous: a –b means a le x < b.) Using Median = l + hf ( n2 - c ), the median is:
30
38.75
40
35.83
Answer: D) 35.83
Explanation: n = 40, n2 = 20. The median class is 30 –40 with l = 30, h = 10, f = 12, c = 13. Median = 30 + 1012(20 - 13) = 35.83. SLO M-09-C-02 · Understanding
20. Class Frequency ------ 100–110 8 110–120 14 120–130 20 130–140 10 140–150 8 (Classes are continuous: a –b means a le x < b.) The mean of this distribution is:
125.5
125
124.33
129.33
Answer: C) 124.33
Explanation: Using midpoints x: sum fx = 7460, sum f = 60, so barx = sum fxsum f = 124.33. SLO M-09-C-02 · Understanding
22. Class Frequency ------ 0–20 6 20–40 10 40–60 16 60–80 12 80–100 6 (Classes are continuous: a –b means a le x < b.) Using Median = l + hf ( n2 - c ), the median is:
51.25
60
40
53.8
Answer: A) 51.25
Explanation: n = 50, n2 = 25. The median class is 40 –60 with l = 40, h = 20, f = 16, c = 16. Median = 40 + 2016(25 - 16) = 51.25. SLO M-09-C-02 · Understanding