Percentage - Study Mode

[#406] The price of a commodity which was Rs. 250 three years ago is Rs. 2000 now. The annual rate of increase in the price is ?
Correct Answer

(A) $$100\%$$

Explanation

Solution: $$eqalign{
& Rightarrow 250{left( {1 + frac{R}{{100}}}
ight)^3} = 2000 cr
& Rightarrow {left( {1 + frac{R}{{100}}}
ight)^3} = frac{{2000}}{{250}} cr
& Rightarrow {left( {1 + frac{R}{{100}}}
ight)^3} = 8 = {left( 2
ight)^3} cr
& Rightarrow left( {1 + frac{R}{{100}}}
ight) = 2 cr
& Rightarrow frac{R}{{100}} = 1 cr
& Rightarrow R = 100 \% cr} $$

[#407] Solve this : (7.9% of 134) - (3.4% of 79) = ?
Correct Answer

7.3

Explanation

Solution: (7.9% of 134) - (3.4% of 79) $$ = left( {frac{{79}}{{10}} imes frac{1}{{100}} imes 134}
ight) - $$ xa0 xa0 $$left( {frac{{34}}{{10}} imes frac{1}{{100}} imes 79}
ight)$$ $$eqalign{
& = frac{{79}}{{1000}} imes left( {134 - 34}
ight) cr
& = frac{{79}}{{1000}} imes 100 cr
& = frac{{79}}{{10}} cr
& = 7.9 cr} $$

[#408] Solve this : 36% of 365 + (?)% of 56.2 = 156.69
Correct Answer

(D) 45

Explanation

Solution: Let 36% of 365 + x% of 56.2 = 156.69 Then, $$ Rightarrow left( {frac{{36}}{{100}} imes 365}
ight) + left( {frac{x}{{100}} imes 56.2}
ight)$$ xa0 xa0 xa0 $$ = 156.69$$ $$eqalign{
& Rightarrow frac{{281}}{{500}}x = 156.69 - 131.4 cr
& Rightarrow frac{{281}}{{500}}x = 25.29 cr
& Rightarrow x = frac{{25.29 imes 500}}{{281}} cr
& Rightarrow x = 45 cr} $$

[#409] Twenty-five percent of Reena's yearly income is equal to seventy-five percent of Anubhab monthly income . If Anubhab yearly income is Rs. 240000, What is the Reena's monthly income ?
Correct Answer

Rs. 60000

Explanation

Solution: Let Reena's yearly income be Rs. x Anubhab monthly income = Rs. $$frac{240000}{12}$$ = Rs. 20000 Then, ⇒ 25% of x = 75% of 20000 ⇒ $$frac{25}{100}$$x = $$frac{75}{100}$$ × 20000 ⇒ $$frac{x}{4}$$ = 15000 ⇒ x = 60000 ∴ Reena's monthly income : = Rs. $$frac{60000}{12}$$ = Rs. 5000

[#410] What will be the answer : 140% of 56 + 56% of 140 = ?
Correct Answer

78.4

Explanation

Solution: = 140% of 56 + 56% of 140 $$eqalign{
& = left( {frac{{140}}{{100}} imes 56}
ight) + left( {frac{{56}}{{100}} imes 140}
ight) cr
& = 78.4 + 78.4 cr
& = 156.8 cr} $$