Statisticshard · Past Paper
If $x_1, x_2...x_n$ are observations such that $\sum (x_i - 2) = 20$ and $\sum (x_i - 5) = -10$, then $n$ is:
A10
B15
C20
D5
✓ Correct Answer: A — 10
$(\sum x - 2n = 20)$ and $(\sum x - 5n = -10)$. Subtracting: $3n = 30 \Rightarrow n = 10$.
Share this question
More from Statistics
- Three fair coins are tossed. What is the probability of getting at least two heads?
- If the mean of $x, x+3, x+6, x+9, x+12$ is 10, then x is:
- A cumulative frequency curve is also known as:
- In which data series is the formula for median position (N/2) used instead of (N+1)/2?
- Find the median of the series: 3, 3.5, 2.5, 4.5, 5, 2, 0.5, 6, 7.