Steps involved in finding a percent of a given number
Step I– Obtain the number, say x.
Step II– Obtain the required percent, say P %.
Step III– Multiply x by P and divide by 100 to obtain the required P % of x
i.e., P% of x = \(\frac{ P}{ 100}\) * x
Illustrative Examples
Example 1: Find
(i) 30% of Rs 180 (ii) 13% of Rs 6500 (iii) 16% of 25 litres
Solution. We know that P% of x is equal to \(\frac{ P }{ 100}\) * x. So, We have
(i) 30% of Rs 180 = Rs ( \(\frac{ 30 }{ 100}\) x 180) = Rs 54
(ii) 13% of Rs 6500 = Rs ( \(\frac{ 13 }{ 100}\) x 6500 ) = Rs 845
(iii) 16% of 25 litres = Rs ( \(\frac{ 16 }{ 100}\) x 25) = 4 litres
Example 2: If 23% of a is 46, then find a.
Solution. We have,
23% of a = \(\frac{ 23 }{ 100}\) x a.
But, 23% of a is given as 46.
Therefore, \(\frac{ 23 }{ 100}\) x a => a = 46 x \(\frac{ 100 }{ 23 }\)
=> a = 200
Example 3: 72% of 25 students are good at Mathematics. How many are not good at it?
Solution. We have,
Number of students who are good at Mathematics
= 72% of 25
= \(\frac{ 72 }{ 100}\) x 25 = 18
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