Total Profit Equation 

The total profit is defined as that the positive difference from the marginal cost to the variable cost. The total profit equation is used to find the profit percentage of the business. The profit equation is shown below.



Profit percentage=`((sell price-cost price)/(cost price))xx100`
In the competitive exams almost have the questions based on this total profit equation, so the students have to gain good knowledge in this profit percentage problems.Problems Using Total Profit Equation
1.Peter  buys a table for Rs. 4200 and spends Rs. 800 on its repairs. If he sells the table for Rs. 6000, his gain percent is?Solution:
Cost Price (C.P.) = Rs. (4200 + 800) = Rs. 5000.
Selling Price (S.P.) = Rs. 6000.
Gain = (S.P.) - (C.P.) = Rs.(6000 - 5000) = Rs. 1000.
Profit %=`((1000/5000)xx100)=20%`

2.The cost price of 20 pencils is the same as the selling price of x penciles. If the profit is 25%, then find the value of x?Solution:
Let C.P. of each pencil be Re. 1 C.P. of x pencils = Rs. x.
S.P. of x articles = Rs. 20.
Profit = Rs. (20 - x).
Therefore `((20-x)/x)xx100=25`
2000 - 100x = 25x
125x = 2000
x = 16.
3.If selling price increased double means, the profit achieved as triples. Find the profit percentage?Solution:
Let C.P. be Rs. x and S.P. be Rs. y.
Then, 3(y - x) = (2y - x)    y = 2x.
Profit = Rs. (y - x) = Rs. (2x - x) = Rs. x.
Therefore profit% = `(x/x)xx100=100%`
4.The profit is 300% of the cost. If the cost increased by 25% but the selling price is same, in what percentage of the selling price is the profit?Solution:
Let C.P.= Rs. 100. Then, Profit = Rs. 300, S.P. = Rs. 400.
New C.P. = 125% of Rs. 100 = Rs. 125
New S.P. = Rs. 400.
Profit = Rs. (400 - 125) = Rs. 275.
Required percentage=`((275/400)xx100=68.75%`


Practice Problems on Total Profit Equation
1.Rose  bought chocolates  at 6 for a rupee. How many for a rupee must he sell to gain 20%?
Answer: 5
2. A boy buys a doll for Rs. 1200 and sells it at a loss of 10%. What is the selling price of the doll?
Answer: Rs.1080