Question

Suppose you have a grandfather who always eats 2 biscuits with one cup of coffee. He eats biscuits only with coffee. A can of biscuits costs $14 and it contains 20 biscuits. A cup of coffee costs 60 cents. He reserves $60/month to he coffee and biscuits. How many cups of coffee will he drink per month?

Answer 1

Answer; 30 cups of coffee per month.

Grandfather always eats 2 biscuits with 1 cup of coffee.

A can of biscuits costs $14 and it contains 20 biscuits.

Cost of 20 biscuits = $14

Cost of 1 biscuit = $14 / 20 = $0.7 or 70 cents.

Cost of 2 biscuits = $0.7 *2 = $1.40

A cup of coffee costs 60 cents.

So, the total cost of 2 biscuits and 1 cup of coffee = $1.40 + $0.60 = $2.00

Thus spending $2, grandfather gets 2 biscuits and 1 cup of coffee. He reserves $60/month for coffee and biscuits.

Now, when grandfather's budget is $2, he gets 2 biscuits and 1 cup of coffee. As the grandfather always eats 2 biscuits with 1 cup of coffee, he maintains the same proportion when his budget rises. So when his budget rises, then the proportionate increase in biscuit and coffee will be same as the proportionate increase in budget.

When grandfather reserves $60/month for coffee and biscuits, his budget increases by 30 times ( $2 * 30) of his budget of $2. Now, as his budget increases by 30 times, his consumption of coffee and biscuits will also increase by 30 times

Thus his consumption of coffee will be = 1 * 30 = 30 cups.

His consumption of biscuits will be = 2 * 30 = 60 biscuits.

So, grandfather will drink 30 cups of coffee per month.

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