Question

All of the following are ways to write 25 percent of N except for: -
(a) 0.25 N
(b) \[\dfrac{25N}{100}\]
(c) \[\dfrac{1}{4}N\]
(d) 25N

Answer 1

Hint: First understand the meaning of percentage then calculate 25 percent of N using the formula given by x % of a = \[\dfrac{x}{100}\times a\]. Once getting an expression for 25 percent of N, try to simplify it in various forms such as decimal form, fractional form to get one of the option odd one out.

Complete step by step answer:
We have been given to find the expression for 25 percent of N. But first we need to understand the meaning of percentage.
In mathematics a percentage is a ratio or number expressed as a fraction of 100. It is often included by using the percent sign, “%”. A percentage is a dimensionless number (pure number); it has no unit of measurement. For example: - if we say 10% of bulbs in the box are defective that means that if the box contains 100 bulbs then 10 bulbs in them are defective while 90 are effective. The percentage formula is given by the relation: -
\[\Rightarrow \] x % of a = \[\dfrac{x}{100}\times a\]
Now, let us come to the question. We have to find 25 percent of N.
\[\Rightarrow \] 25% of N = \[\dfrac{25}{100}\times N\], stating option (b) is correct.
Now, dividing 100 by 25 we get 4.
\[\Rightarrow \dfrac{25}{100}N=\dfrac{1}{4}N\], stating option (c) is correct.
In decimal form, \[\dfrac{25}{100}=0.25\], hence,
\[\Rightarrow \dfrac{25}{100}N=0.25N\], stating option (a) is correct.
Therefore, we can see that 25 N which is option (d) is the odd one out.

So, the correct answer is “Option D”.

Note: One may note that we have used the method of eliminating the options to get the one option odd one out. Sometimes this method is very helpful in competitive exams mainly in the chapter of algebra. What we did in the above solution is that first we found the expression for 25 % of N and then used divisions to get other options.