Plz it really is challenging

Question

If the mean of A and B is 20 the mean of B and C is 24 and the mean of A B and C is 18 what is the mean of A and C

Answer 1

Question: If the mean of A and B is 20 the mean of B and C is 24 and the mean of A B and C is 18 what is the mean of A and C.

The mean of A and B is 20. i.e. (A + B)/2 = 20, or A + B = 40.

The mean of B and C is 24. i.e. (B + C)/2 = 24, or B + C = 48.

The mean of A, B and C is 18. i.e. (A+B+C)/3 = 18, or A+B+C = 54.

The equations we have are:

A + B = 40     ---------------- (1)

B + C = 48    ----------------- (2)

A+B+C = 54  ----------------- (3)

(3) - (1)

C = 14

(3) - (2)

A = 6

Using A = 6 in (1),

B = 34

Mean of A and C is (A + C)/2 = (6 + 14)/2 = 10

Answer; Mean of A and C is 10

Answer 2

me assume bi "meen" yu meen yu want AVERAEJ

so (a+b)/2=20, or a+b=40....or b=40-a

(b+c)/2=24, so b+c=48...or c=48-b...or c=48-(40-a)...c=a+8

(a+b+c)/2=18, so a+b+c=36

a+(40-a) +(a+8)=36...a+48=36...a=36-48...a=-12

b=40-a=40+12....b=52

c=a+8...8-12....c=-4

Answer 3

Given :  ( A and B ) = 20 , ( B and C ) = 24 , ( A, B and C ) = 18

Ask : ( A and C ) = ?

Solution :

mean of :

A + B is 40 since ( A + B ) / 2 = 20  ( 1st Equation )

B + C is 48 since ( B + C ) / 2 = 24  ( 2nd Equation )

A + B + C is 54 since ( A + B + C ) / 3 = 18  ( 3rd Equation )

Find B:

A + B = 40

B = 40 - A

Find C:

B + C = 48

C = 48 - B

Substitute the value of B and C to the 3rd Equation to find B:

A + B + C = 54

A + ( 40 - A ) + ( 48 - B ) = 54

A + 40 - A + 48 - B = 54

88 - B = 54

- B = 54 - 88  ( Addition Property of Equality )

- B = - 34

B = 34   (dividing both sides by - 1 )

 

Substitute the value of B to get A:

A + B = 40

A + 34 = 40

A = 6

Substitute the vlue of B to the 2nd Equation to get C:

B + C = 48

34 + C = 48

.

Then, the mean of A + C is 10.