question_answer 1)

Cost of a dozen pens is ` 180 and cost of 8 ball pens is ` 56. Find the ratio of the cost of a pen to the cost of a ball pen.

Answer:

                Given, cost of 12 pens = ` 180 \[\therefore \] Cost of 1 pen\[\text{=}\frac{\text{Total}\,\text{cost}\,\text{of}\,\text{pens}}{\text{Number}\,\text{of}\,\text{pens}}\] = ` \[\frac{180}{2}=\] ` 15 [\[\because \]1 dozen = 12 unit] Also given, cost of 8 ball pens = ` 56 \[\therefore \] Cost of 1 ball pen \[\text{=}\frac{\text{Total}\,\text{cost}\,\text{of}\,\text{ball}\,\text{pens}}{\text{Number}\,\text{of}\,\text{ball}\,\text{pens}}\] = ` \[\frac{56}{8}=\]` 7 Now, required ratio \[\text{=}\frac{\text{Cost}\,\text{of}\,\text{1pen}}{\text{Cost}\,\text{of}\,\text{1}\,\text{ball}\,\text{pen}}=\frac{Rs.15}{Rs.7}=\frac{15}{7}=15:7\]