the average of first 4 numbers out of 5 numbers is 18 whereas average of last four numbers is 13. if the first no is 23 then what is the last no
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Answer:
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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}average=
3
Sum of first three numbers
16 = \frac{a+b+c}{4}16=
4
a+b+c
16 \times 3 =a+b+c16×3=a+b+c
48 =a+b+c48=a+b+c ---1
The avg. of last 3 number is 14
average = \frac{\text{Sum of last three numbers}}{3}average=
3
Sum of last three numbers
14 = \frac{a+b+c+d}{4}14=
4
a+b+c+d
14 \times 3 =b+c+d14×3=b+c+d
42 =b+c+d42=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+c48=16−d+b+c
32= -d+b+c32=−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+3748=a+37
48-37 =a48−37=a
11=a11=a
Substitute the value of a in 3
11+d=16
d=16-11
d=5
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