In the diagram, RT is a tangent to the circle at R, < PQR = 70\(^o\), < QRT = 52\(^o\), < 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
waec 2019mathematics

The correct answer is B. 6.8

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 Previous question Next question