2024 · Q81
Three amounts x, y, z are such that y is the compound interest on x; and z is the compound interest on y. The rate of interest per annum and the time period in years are same. Which one of the following is correct?
Elementary MathematicsSimple and Compound Interest
- Ax2 = yz
- By2 = zx
- Cz2 = xy
- Dx = yz
Explanation
Let k = (1+r)^t − 1 be the compound-interest factor. Then y = kx (CI on x) and z = ky (CI on y). Squaring: y² = k²x². Meanwhile zx = (ky)(x) = k²x² as well. Hence y² = zx — option B.