Question

buying any items at 10% less and selling it 10 % more doubles the profit for a mom -n-pop shop given that all prices have to be whole numbers . which of the following could have been the cost price?​

Answer 1

Solution :-

Let us assume that, cost price of the item is Rs.x and selling price is Rs.y .

so,

→ Profit = SP - CP = Rs.(y - x)

now,

→ New cost price = 10% less = 90% of x = (90 * x)/100 = Rs.(9x/10)

and,

→ New selling price = 10% more = 110% of y = (110 * y)/100 = Rs.(11y/10)

then,

→ New profit = New SP - New CP = (11y/10 - 9x/10) = Rs.(11y - 9x)/10

A/q,

→ New profit = 2 * Profit

→ (11y - 9x)/10 = 2(y - x)

→ 11y - 9x = 20(y - x)

→ 11y - 9x = 20y - 20x

→ 20x - 9x = 20y - 11y

→ 11x = 9y

since x is a whole number , x must be divisible by 9 .

Check options now, CP which is divisible by 9 will be our answer .

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