Percentage - Study Mode

[#346] In a town, the population was 8000. In one year, male population increased by 10% and female population increased by 8% but the total population increased by 9%. The number of males in the town was :
Correct Answer

(A) 4000

Explanation

Solution: Note : In such type of questions use allegation method to save your valuable time. Required number of males = $$frac{8000}{(1 + 1)}$$ xa0× 1 = 4000

[#347] The population of a village is 25000. One-fifth are females and the rest are males, 5% of males and 40% of females are uneducated. What percentage on the whole are educated ?
Correct Answer

(B) 88%

Explanation

Solution: Number of females : = 25000 × $$frac{1}{5}$$ = 5000 Number of males : = 25000 - 5000 = 20000 Number of educated females : = 5000 × $$frac{60}{100}$$ = 3000 Number of educated males = 20000 × $$frac{95}{100}$$ = 19000 Total educated population = 22000 Percentage of educated population = $$frac{22000}{25000}$$ xa0× 100 = 88%

[#348] In a factory, the production of cycles rose to 48400 from 40000 in 2 years. The rate of growth per annum is ?
Correct Answer

(D) 10%

Explanation

Solution: The production of cycles rose to 48400 from 40000 in 2 years ⇒ Present production = 40000 ⇒ After two years = 48000 ⇒ Time = 2 years ⇒ Rate of increment = ? According to the question, Production after 2 years = Present production $${left( {1 + frac{{ ext{R}}}{{100}}}
ight)^t}$$ $$eqalign{
& Rightarrow 48400 = 40000{left( {1 + frac{{ ext{R}}}{{100}}}
ight)^2} cr
& Rightarrow frac{{484}}{{400}} = {left( {1 + frac{{ ext{R}}}{{100}}}
ight)^2} cr
& Rightarrow 1 + frac{{ ext{R}}}{{100}} = frac{{22}}{{20}} cr
& Rightarrow frac{{ ext{R}}}{{100}} = frac{1}{{10}} cr
& Rightarrow { ext{R}} = 10\% cr} $$ ⇔ Rate of increment = 10%

[#349] A student scored 32% marks in science subjects out of 300. How much should he score in language papers out of 200 if he is to get overall 46% marks ?
Correct Answer

(B) 67%

Explanation

Solution: Total marks = (300 + 200) × $$frac{46}{100}$$ = 230 Marks obtained by the students in science = 300 × $$frac{32}{100}$$ = 96 Required marks in language paper = (230 - 96) = 134 Required percentage = $$frac{134}{200}$$ × 100 = 67% Hence, required percentage = 67%

[#350] Present population of a village is 67600, It has been increasing annually at the rate of 4%. What was the population of the village two years ago ?
Correct Answer

(A) 62500

Explanation

Solution: Let the initial population = x According to the question, $$eqalign{
& x imes frac{{104}}{{100}} imes frac{{104}}{{100}} = 67600 cr
& x = frac{{67600 imes 100 imes 100}}{{104 imes 104}} cr
& ,,,,,, = 62500 cr} $$ Hence required population = 62500