A student multiply a number by \(\frac{7}{4}\) instead of \(\frac{3}{5}\).  Find the percentage of error in calculation.

191\(\frac{2}{3}\)%

Let a Number which is L.C.M. of 4 & 5

i.e. (20)

Now,

⇒ Wrong Answer  = 20 × \(\frac{7}{4}\) = 35 

⇒ Correct Answer = 20 × \(\frac{3}{5}\) = 12

⇒ Difference = 35 - 12 = 23

⇒ Error percentage = \(\frac{23}{12}\) × 100% = 191\(\frac{2}{3}\)%