In a class of 45 students, 28 offer chemistry and 25 offer Biology. If each student offers at least one of the two subjects, calculate the probability that a student selected at random from the class the class offers chemistry only.

  • A \(\frac{2}{9}\)
  • B \(\frac{4}{9}\)
  • C \(\frac{5}{9}\)
  • D \(\frac{7}{9}\)
waec 2017mathematics

The correct answer is B. \(\frac{4}{9}\)

28 - x + x + 25 - x = 45

53 - x = 45

x = 53 - 45

x = 8

chemistry only = 28 - 8

= 20

Probability = \(\frac{20}{45}\)

= \(\frac{4}{9}\)

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