Question

The mean of 7 numbers is 11. Five of the numbers are 3, 17, 20, 4 and 15.
The remaining two numbers are each equal to y. Find
() the sum of the 7 numbers,
(ii) the value of y.
The mean height of 20 boys and 14 girls is 161 cm. If the mean height of the
14 girls is 151 cm, find the mean height of the 20 boys.​

Answer 1

Answer:

59+2y/7=11

59+2y=77

2y=18

y=9.

sum of 7 numbers is 59+18=77

Answer 2

Average of no.=11

sum of all no. /total no.=11

(3+17+20+4+15+y+y)/7=11

59+2y=77

2y=18

y=9

(i)the sum of no.s is 77

(ii)the value of y is 9

total of hieght of 20boys =xcm

total hieght of 14girls =ycm

mean hieght of 14girls=151cm

y/14=151

y=2114

mean of all students=161cm

(x+y)/(20+14)=161

x+y=161×34

x+2114=5474

x=5474-2114

x=3360

mean hieght of 20 boys=3360/20

=168cm

hope both the answers help

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