The price of an article is reduced by 10% and its daily sale increased by 15%. Find the net percent effect on the daily sale.

Correct option is D

Given:

Selling price is reduced by 10%

Daily sale increased by 15%

Formula Used:

​$$Percentage = \frac{New\ Value - Old\ value}{Old\ Value} \times 100$$​​

Solution:

Let the price of the article be Rs 100 and the daily sale be 100 units.

Daily revenue = 100 $$\times$$​ 100 = Rs 10,000

Now,

New rate = Rs 90

Increase in sale = 115

New revenue = 115 $$\times$$​ 90 = Rs 10,350

Increase = 10,350-10,000 = Rs 350

Increase percentage  = $$\frac{350}{10,000} \times 100 = 3.5\%$$ 

Thus, the daily sale increased by 3.5%

 Alternative Method:

Successive Percent = $$x + y - \frac{(x)(y)}{100}$$​​

Successive Percent = $$-10+15 + \frac{(-10)(15)}{100}$$​​

​$$= 5 - 1.5 =3.5$$​​

(+) sign indicates there’s an increase