In the diagram, RT is a tangent to the circle at R, ∠ PQR =
MATHEMATICS
WAEC 2019
In the diagram, RT is a tangent to the circle at R, ∠ PQR = 70°, ∠ QRT = 52°, ∠ QSR and ∠ PRQ = x. Calculate the variance of 2, 4, 7, 8 and 9
- A. 7.2
- B. 6.8
- C. 3.5
- D. 2.6
Correct Answer: B. 6.8
Explanation
x 2 4 7 8 9 | (\(\bar{x} - \bar{x}\)) -4 -2 1 2 4 | (\(\bar{x} - \bar{x})^2\) 16 4 1 4 9 _________ \(\sum (x - x)^2\) = 34 |
\(\bar{x} = \frac{2 + 4 + 7 + 8 + 9}{5} = 6
variance = \(\frac{34}{5}\)
= 6.8
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