Average - Study Mode

[#361] The average expenditure of a man for the first five months of a year is Rs. 5000 and for the next seven months it is Rs. 5400. He saves Rs. 2300 during the year. His average monthly income is-
Correct Answer

(A) Rs. 5425

Explanation

Solution: Total yearly income = Rs. (5000 × 5 + 5400 × 7 + 2300) = Rs. (25000 + 37800 + 2300) = Rs. 65100 ∴ Average monthly income = Rs. $$left( {frac{{65100}}{{12}}}
ight)$$ = Rs. 5425

[#362] The average weight of 16 boys in a class is 50.25 kgs and that of the remaining 8 boys is 45.15 kgs. Find the average weight of all the boys in the class.
Correct Answer

(C) 48.55 kgs

Explanation

Solution: Required mean $$eqalign{
& = left( {frac{{50.25 imes 16 + 45.15 imes 8}}{{16 + 8}}}
ight) cr
& = left( {frac{{804 + 361.20}}{{24}}}
ight) cr
& = frac{{1165.20}}{{24}} cr
& = 48.55 cr} $$

[#363] A library has an average of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is-
Correct Answer

(D) 285

Explanation

Solution: Since the month begins with a Sunday, so there will be five Sundays in the month. ∴ Required average $$eqalign{
& = left( {frac{{510 imes 5 + 240 imes 25}}{{30}}}
ight) cr
& = frac{{8550}}{{30}} cr
& = 285 cr} $$

[#364] In the first 10 overs of a cricket game, the run rate was only 3.2. The run rate in the remaining 40 overs to reach the target of 282 run is :
Correct Answer

(C) 6.25

Explanation

Solution: Total run till 10 overs is = 3.2 × 10 = 32 Remaining runs = 282 - 32 = 250 250 runs make in 40 overs so average runs per overs = $$frac{250}{40}$$ = 6.25

[#365] The average height of 30 boys out of a class of 50 is 160 cm. If the average height of the remaining boys is 165 cm, the average height of the whole class (in cm) is :
Correct Answer

(B) 162

Explanation

Solution: Average height of the whole class $$eqalign{
& = frac{{30 imes 160 + 20 imes 165}}{{50}} cr
& = frac{{3 imes 160 + 2 imes 165}}{5} cr} $$ = 96 + 66 = 162 cm