Question

the total cost of 15 newspapers
is rs 37. 50 find the cost of 25 newspaper​

Answer 1

Unitary method :

Cost of 15 newspapers = Rs.37.5

Cost of one nespaper = 37.5/15

Cost of 25 newspapers = 37.5/15 * 25

$= \frac{37.5}{15} \times 25$

$= \frac{37.5}{3} \times 5$

= 12.5 * 5

= 62.5

So, Cost of 25 newspapers = Rs. 62.5

Proportion method :

Let the cost of 25 newspapers be x

Proportion : 15 : 25 : : 37.5 : x

We know that, Product of extemes = Product of means

Here extremes = 15, x; means = 25, 37.5

$\tt{15\times x = 25\times37.5}$

$\tt{15x = 937.5}$

$\tt{x =\frac{937.5}{15}}$

$\tt{x =\frac{9375}{150}}$

$\tt{x = 62.5}$

Therefore cost of 25 newspapers is Rs. 62.5.

Answer 2

It is given that the cost of 15 newspapers is Rs. 37.50 and we are supposed to find the cost of 25 newspapers.

Method being used: Unitary Method.

Unitary Method:

Definition: In this method, we will first find the cost of 1 article and then multiply the cost with the number of articles we are supposed to find the total cost of.

Process: The process for finding the cost of an article is quite simple. All that we have to do is to divide the total cost for those articles by the number of articles.

$Cost \: \: of \: \: 1 \: \: newspaper = \frac{37.50}{15} \\ \\ = \frac{375}{150} = \frac{75}{30} = \frac{15}{6} = \frac{5}{2} = Rs.2.5$

Now we shall find the cost of 25 newspapers by multiplying the cost of 1 article I.e. Rs. 2.5 with 25.

Cost of 25 newspapers = 2.5 * 25 = Rs. 62.5.

Therefore, the cost of 25 newspapers is Rs. 62.5.