The mean weight of a group of seven boys is 56 kg. The individual weights (in kg) of six of them are 52, 57, 55, 60, 59 and 55. Find the weight of the seventh boy.
Total weight of 6 boys = (52 + 57 + 55 + 60 + 59 + 55) kg
= 338 kg.
Weight of the 7th boy = (total weight of 7 boys) – (total weight of 6 boys)
= (392 – 338) kg
= 54 kg.
Hence, the weight of the seventh boy is 54 kg.
Workspace
The average height of 30 boys was calculated to be 150 cm. It was detected later that one value of 165 cm was wrongly copied as 135 cm for the computation of the mean. Find the correct mean.
The aggregate monthly expenditure of a family was $ 6240 during the first 3 months, $ 6780 during the next 4 months and $ 7236 during the last 5 months of a year. If the total saving during the year is $ 7080, find the average monthly income of the family.
According to given information 19A + 95 = 20 (A + 4)
So A = 15
Now average runs after 20th innings = 15 + 4 = 19
Workspace
The average of 8 readings is 24.2, out of which the average of first two is 18.5 and that of next three is 21.1. If the sixth reading is 5 less than seventh and 7 less than eighth, what is the sixth reading?
P =18 km , Q = 16 km , R =30 km , X = 10 km/hr, Y= 8 km/hr & Z = 6 km/hr
=
= 80/11
The average speed of the whole distance = 80/11 = km/hr.
Workspace
There are two batches A and B of a class. Batch A consists of 36 students and batch B consists of 44 students. Find the average weight of whole class, if average weight of batch A is 40 kg and that of batch B is 35 kg.
1)Sum of observations = Average x No. of observations
= 46 x 40 = 1840
2)Correct sum = Sum of observations + (38 – 33)
= 1840 + (5)
= 1845
Corrected Mean Value =
Corrected Sum
=
1845
= 46.125
No. of Observations
40
Workspace
In a cricket match, 6 players had an average X of their runs. Average increases by 10 runs, if seventh player makes a score of 112 runs. What is the average of first 6 players.
Average increases by 10, when seventh player makes a score of 112 runs.
Therefore, average of 7 players = X + 10
Average =
Sum of Scores
——- (1)
Number of Players
Here, average = X, number of players = 6
Hence, Sum of scores = 6X
Score of 7 players = (Score of 6 players + score of 7 player) = (6X + 112) ——- (2) Total average = (X + 10) ——— (3)
Substitute (2) and (3), in (1)
(X + 10)
(6X + 112)
7
Solving we get,
X = 42
Average of first 6 players = 42
Workspace
The average weight of 39 men travelling to Ladakh is 30. If an obese man with weight 130 kg join them. What will be the average weight of the people travelling to Ladakh?
If the weight of the man would have been 30, then the average weight would have been the same. So, the extra 100 kg that the obese man brings with him would be distributed equally amongst all of them, i.e. 100/40 = 2.5
So, the average becomes 30 + 2.5 = 32.5
Workspace
The average salary of 30 officers in a firm is Rs.120 and the average salary of laborers is Rs. 40. Find the total number of laborers if the average salary of the firm is Rs. 50.
Average of 4 terms = 20
Hence, the total sum of 4 terms = 80
Let terms be A,B,C,D
So, the sum will be A+B+C+D =80
Given, 3A = B+C+D
So, 4A = 80,
A = 20
Workspace
For 9 innings, Boman has an average of 75 runs. In the tenth inning, he scores 100 runs, thus increasing his average . His new average is
