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JAMB Mathematics 1983 Question 9

Question 9

Fractions, Decimals and Approximation

If 0.0000152 × 0.00042 = A × 10B, where 1 ≤ A < 10, find A and B.

  1. A.A = 9, B = 6.38
  2. B.A = 6.38, B = −9
  3. C.A = 6.38, B = 9
  4. D.A = 6.38, B = −1
  5. E.A = 6.38, B = 1.
Show the answer and explanation

Answer: B (A = 6.38, B = −9)

Explanation

1.52 × 10⁻⁵ × 4.2 × 10⁻⁴ = 6.384 × 10⁻⁹, so A ≈ 6.38 and B = −9.