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# Cost of a dozen pens is Rs 180 and the cost of 8 ball pens is Rs 56. Find the ratio of the cost of a pen to the cost of a ball pen. Verified
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Hint: The unitary method, in essence, is all about finding the “per unit value”. The unitary method is a technique for solving a problem by first finding the value of a single unit.

Now use the unitary method to find the value of a single unit.
Cost of a dozen pens (12 pens) $= Rs.180$
Cost of one pen $= \dfrac{{180}}{{12}}$
Cost of one pen, ${C_1} = Rs.15$
Now, Cost of 8 ball pens $= Rs.56$
Cost of one ball pen $= \dfrac{{56}}{8}$
Cost of one ball pen, ${C_2} = Rs.7$
Now, take the ratio of cost of a pen to the cost of a ball pen.
$\dfrac{{{C_1}}}{{{C_2}}} = \dfrac{{15}}{7}$
So, the ratio of the cost of a pen to the cost of a ball pen is 15:7
Note:Whenever we face such types of problems we use some important points. First we find the value of a single unit by using a unitary method then after the take ratio we can get the required answer.
Last updated date: 01st Oct 2023
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