A student divided a number by 10 instead of multiplying it by 10. What is the percentage error? MCQ with Answer and Explanation

Explanation:
Let MP=100, CP=80, SP=100, profit% = (20/80)×100 = 25%.

Explanation:
(1.6N)/(0.8D) = 2N/D = 5/8 → N/D = 5/16. Wait, 2N/D = 5/8 → N/D = 5/16. That's option B. So I'll set correct B. But I have options: 3/8, 5/16, 5/12, 7/16. So B. I'll adjust options: A 3/8, B 5/16, C 5/12, D 7/16. So answer B.

Explanation:
60% of 50 = 30 boys.