Question

If the cost of dozens of soaps is Rs. 153.80. What will be the cost of 15 such soaps?

Answer 1

Hint:
It is given that the cost of a dozen soaps i.e. 12 soaps is Rs. 153.80.
To find the cost of 15 soaps, we first need to find the cost of one soap by dividing the cost of 12 soaps by 12.
Thus, find the cost of 15 soaps by finding the product of cost of one soap and 15.

Complete step by step solution:
Here, it is given that the cost of a dozen soaps are Rs. 153.80.
Now, a dozen soaps is equal to 12 soaps.
Thus, the cost of 12 soaps is Rs. 15.80.
To find the cost of one soap, divide the cost of 12 soaps by 12.
 $\therefore $ Cost of one soap $ = \dfrac{{153.80}}{{12}}$
=12.81667
=12.82
Thus, the cost of one soap is Rs. 12.82.
Now, to find the cost of 15 soaps.
To do so, we need to multiply the cost of one soap by 15, to get the cost of 15 soaps.
 $\therefore $ Cost of 15 soaps $ = 15 \times 12.82 \\
=192.3$

Thus, the required cost of 15 soaps is Rs. 192.3.

Note:
Alternate method:
It is given that the cost of a dozen soaps is Rs. 153.80.
Now, let the cost of 15 soaps be Rs. X.
So, Cost of 12 soaps = 153.80
Cost of 15 soaps = x
Thus, by unitary method, we can solve the above equation as
 $12 \times x = 15 \times 153.80$
 $
  \therefore x = \dfrac{{2307}}{{12}} \\
  \therefore x = 192.25 \\
  \therefore x = 192.3 \\
 $
Thus, the cost of 15 soaps is Rs. 192.3.