Question

frist three numbers average is 18. then last three numbers average is 14 and frist and last sum is 16 then find last numbe​

Answer 1

Answer:

5

Step-by-step explanation:

Let the four numbers be a ,b,c,d

The average of first 3 of 4 numbers is 16

average = \frac{\text{Sum of first three numbers}}{3}

16 = \frac{a+b+c}{4}

16 \times 3 =a+b+c

48 =a+b+c ---1

The avg. of last 3 number is 14

average = \frac{\text{Sum of last three numbers}}{3}

14 = \frac{a+b+c+d}{4}

14 \times 3 =b+c+d

42 =b+c+d ---2

The sum of first and last number is 16

a+d=16 ---3

Substitute the value of a from 3 in 1

48 =16-d+b+c

32= -d+b+c --- 4

Add 2 and 4

42+32=b+c+d+b+c-d

74=2(b+c)

b+c= 37

Substitute the value of b+c in 1

48 =a+37

48-37 =a

11=a

Substitute the value of a in 3

11+d=16

d=16-11

d=5

Hence last no is 5

Step-by-step explanation:

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