Percentage - Study Mode

[#126] If the sum of 40% of a number and 30% of the same number is 70, then the number is:
Correct Answer

(B) 100

Explanation

Solution: Let, number = x 40% of x + 30% of x = 70 70% of x = 70 x = 100

[#127] Two candidates P and Q contested in an election. 70% of the registered voters are P supporters. If 60% of the P supporters and 30% of the Q supporters are expected to vote for candidate P, then what percentage of the registered voters are expected to vote for candidate P?
Correct Answer

(B) 51%

Explanation

Solution: Given: Registered voters for P supporters = 70% 60% of the P supporters and 30% of the Q supporters are expected to vote for candidate P. Concept used: Let total voters be 1000 Then 700 are P supporters and 300 are Q supporters Total votes of P ⇒ 60% of 700 + 30% of 300 ⇒ 420 + 90 ⇒ 510 Percentage of P voters ⇒ $$510 imes frac{{100}}{{1000}}$$ ⇒ 51% Hence, the required value is 51%

[#128] The actual area of a rectangle is 60 Cm 2 , but while measuring its length a student decreases it by 20% and the breadth increases by 25%. The percentage error in area, calculated by the student is :
Correct Answer

(D) No change

Explanation

Solution: 100 === 25% ↑===> 125 ===> 20% ↓===> 100
So there is no change in the area of rectangle Alternatively : Let area be 1 Area of rectangle, = l × b = 0.8 × 1.25 = 1

[#129] The cost of packaging of the mangoes is 40% the cost of fresh mangoes themselves. The cost of mangoes increased by 30% but the cost of packaging decreased by 50%, then the percentage change of the cost of packed mangoes, if the cost of packed mangoes is equal to the sum of the cost of fresh mangoes and cost of packaging :
Correct Answer

(B) 7.14%

Explanation

Solution: Cost of fresh mangoes + Cost of packaging = Total cost Let initial Cost of fresh, mangoes = 100 Then, packaging cost = 40 Thus, Initial total cost = 100 + 40 = 140 After increasing in cost of fresh mangoes 30%, Cost of fresh mangoes = 130 And cost of packing go down by 50 % so, Cost of packing = 20 Now Total cost = 130 + 20 = 150 Increased cost = 150 - 140 = 10 % increased = $$ = frac{{10 imes 100}}{{140}} = 7.14\% $$

[#130] 220% of a number X is 44. What is 44% of X.
Correct Answer

(A) 8.8

Explanation

Solution: Given, 220% of X = 44 Or, X = 20 Thus, 44% of 20 $$ = frac{{44 imes 20}}{{100}} = 8.8$$