23% of 45 is what percent of 69?
This is a typical grade 4 competition Math problem.
23% of 45 is what percent of 69?
The conventional solution is to simply do the arithmetic:
23% of 45 = 0.23 x 45 = 10.35 (By long multiplication)
10.35/69 = 0.15 = 15% (by long division)
This is actually algebra, but instead of asking the student for the value of x we asked “what percent of.” But that is another story. 🙂
An imaginative MATH-Inic student will have an alternative solution using logic.
Notice that 23 is 1/3 of 69 and remember that 45 is 3 * 15. Mentally, our MATH-Inic student will think:
- 23% of 45 = 69/3 % of 3*15
- which is the same as 69% of 15
- which is the same as 15% of 69
- which means 15% is our answer
Effectively, he gave the answer from logic instead of from long multiplication and long division!
