Statisticshard · Past Paper
A class has 20 boys and 30 girls. The mean height of boys is 150 cm and girls is 140 cm. What is the mean height of the whole class?
A144 cm
B145 cm
C146 cm
D148 cm
✓ Correct Answer: A — 144 cm
Combined mean = (20*150 + 30*140) / 50 = (3000 + 4200) / 50 = 7200 / 50 = 144 cm.
Share this question
More from Statistics
- If the sum of squares of deviations from the mean is zero, then:
- Mode of the data 7, 8, 9, 10, 7, 8, 7 is:
- What is the arithmetic mean of the first five prime numbers?
- A box contains 90 discs numbered 1 to 90. If one disc is drawn, what is the probability that it bears a two-digit number?
- The mean of the first $n$ natural numbers is: