Home » (begin{array}{c|c} text{Age in years} & 10 & 11 & 12 \ hline text{Number of pupils}…

(begin{array}{c|c} text{Age in years} & 10 & 11 & 12 \ hline text{Number of pupils}…

(begin{array}{c|c} text{Age in years} & 10 & 11 & 12 \ hline text{Number of pupils} & 6 & 27 & 7end{array})
The table above shows the number of pupils in each age group in a class. What is the probability that a pupil chosen at random is at least 11 years old?

  • A.
    (frac{27}{40})
  • B.
    (frac{17}{20})
  • C.
    (frac{33}{40})
  • D.
    (frac{3}{20})
Correct Answer: Option B
Explanation

Total number of pupils = 7 + 27 + 6 = 40

n(at least 11 years old) = 27 + 7 = 34.

P(picking a pupil who is at least 11 years old) = (frac{34}{40} = frac{17}{20}).

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