Problem Solving

Source: e-GMAT

A publication company launched two special magazines M1 and M2 at the same retail price of $10. On M1, two successive discounts of 10% and 20% were given, whereas M2 was offered at a single discount of 30%. What is the difference between the final selling prices of M1 and M2?

A. 0
B. 20 cents
C. 40 cents
D. 60 cents
E. 80 cents

The AO is B

Company launched 2 magazines $$M_1\ and\ \ M_2$$ both at the rate of $$10\ dollar$$
M1= 2 successive discounts of 10% and 20%
M2= 1 discount of 30%
Find the difference between the final selling price of M1 and M2
$$Find\ Selling\ price\ of\ M_1\ =10\cdot\left(1-10\%\right)\ \cdot\left(1-20\%\right)$$
$$Find\ Selling\ price\ of\ M_1\ =10\cdot\left(1-0.1\right)\ \cdot\left(1-0.2\right)$$
$$Find\ Selling\ price\ of\ M_1\ =10\cdot0.9\cdot0.8$$
$$Find\ Selling\ price\ of\ M_1\ =7.2\ dollar$$
$$Find\ selling\ price\ of\ \ M_2\ =10\cdot\left(1-30\%\right)\ $$
$$Find\ selling\ price\ of\ \ M_2\ =10\cdot\left(1-0.3\right)\ $$
$$Find\ selling\ price\ of\ \ M_2\ =10\cdot\left(0.7\right)\ $$
$$Find\ selling\ price\ of\ \ M_2\ =7\ dollars$$

Difference between the final selling point of M1 and M2 = (7.2-7) dollars = 0.2 = 20 cents
$$answer\ is\ option\ B$$