Sum of marks of 7 students = Mean x Number of students
= 226 x 7 = 1582
Now, total marks of 6 students = (340 + 180 + 260 + 56 + 275 + 307) = 1418
? Marks obtained by seventh students
= Total marks of seven students - Total marks of the six student
= 1582 - 1418
= 164
Total number of all students of the class = 30 x 45 = 1350
? New average after adjustment = (1350 - 45 + 15)/30 = 1320/30 = 44
According to the basic formula of average,
Average(A)= Sum (S) / Number(N)
? 38 = S/50
? S = 38 x 50 = 1900
Sum of remaining number after eliminating 45 and 55
= 1900 - (45 + 55) = 1800
Average of remaining numbers = (Sum of remaining number) / (Remaining number)
= 1800 / ( 50 - 2)
= 1800/48
= 37.5
Mean = (sum of observation) / (number of observation)
Sum of observation is given as = 70
Number of observation = 20
? Mean = 70/20 = 3.5
But, here observation starts from= 23.
? Mean = 23 + 3.5 = 26.5
Total distance = (200 + 300 + 500) = 1000
Total time = 200/40 + 300/20 + 500/10 = 5 + 15 + 50 = 70 hr
Average speed = Total distance / Total time =1000 / 70 = 14.2857 Km/hr.
Let the height of A , B, C be y cm, y cm and (y - 2) cm respectively
Then, y + y + (y - 2) = 163 x 40 - 162 x 37
? 3y - 2 = 526
? y = 176 cm
Total age of 4 member = 25 x 4 = 100 yr
Total age of 5 members including the head
= 5 x (25 + 25 x 20/100)
= 5 x 30 = 150 yr
? Age of the head = 150 - 100 = 50 yr
Total age of 3 woman = 2 X 11 + (32 + 33 + 34)
= 22 + 99 = 121 yr.
? Average age of 3 woman = 121/3 = 401/3 yr
Total weight of 2 men
= 1 x 10 + (42 + 38) = 10 + 80 = 90 kg
? Average weight of 2 men = 90/2 = 45 kg
Given that total number of students = 150 = ( n1+ n2) and
Mean weight of 150 students = 60 kg.
The mean weight of boys a1= 70 kg and
The mean weight of girls a2 = 55 kg
Let n1 and n2 be the number of boys and girl, respectively.
? n1 + n2 = 150 ...(i)
11 n1 + 11 n2 = 1650 ...(ii)
Average weight = (n1 a1 + n2 a2) / (n1 + n2)
? 60 = (70 n1 + 55n2)/150
? 70 n1 + 55n2 = 9000
? 14n1 + 11n2 =1800 ...(iii)
On subtracting Eq. (ii) from Eq. (iii), we get
3n1 = 150 ? n1 = 50
Hence, required number of boys is 50.
Monthly income of 4 persons = 7350 x 4 = ? 29400
Monthly income of 3 person (excluding the dead person) = 6500 x 3 = ? 19500
? Monthly income of dead person = 29400 - 19500 = ? 9900
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