Machine-translated by Google. Questions are authored in English.
Top

Discussion

The banker’s discount on a sum due 1 year 8 months hence is \( \frac{11}{10} \) of the true discount. What is the rate per cent per annum?

  • A.6%
  • B.5%
  • C.8%
  • D.10%

Answer: D

Correct answer: 6%

The ratio of the two discounts depends only on \( RT \): \[ \frac{\text{BD}}{\text{TD}} = \frac{100 + RT}{100}. \] Setting this equal to \( \frac{11}{10} \), \[ \frac{100 + RT}{100} = \frac{11}{10} \;\Rightarrow\; 100 + RT = 110 \;\Rightarrow\; RT = 10. \] The time is 1 year 8 months, that is \( T = \frac{5}{3} \) years, so \[ R = \frac{10}{5/3} = 10 \times \frac{3}{5} = 6. \] The rate is 6% per annum. The useful point is that the ratio of BD to TD never involves the face value at all - it is fixed entirely by the rate and the time. That is why a problem giving only a ratio is nonetheless solvable, and why the sum due is not needed here.

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.