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The lost pair of weight can be found by subtracting the a known pair from
the total weight leaving the value of the lost pair.
The lost weight of a pair of boys is 120 kg
Reasons:
Let a, b, c, and d represent the weights of the four boys, we have;
The number of ways of selecting pairs (two boys) of boys from a group of
four is given using combination formula as follows;
[tex]_nC_r = \dfrac{n!}{r! \cdot (n - r)!}[/tex]
Which gives;
[tex]_4C_2 = \dfrac{4!}{2! \cdot (4 - 2)!} = 6[/tex]
₄C₂ = 6
Therefore, the weights of the pairs are;
a + b = 110
a + c = 112
a + d = 113
b + c = 118
b + d = 121
c + d = Lost weight
a + b + c + d = 230 (given)
Therefore;
The lost weight, c + d = 230 - (a + b)
Which gives;
c + d = 230 - (110) = 120
The lost weight = c + d = 120
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Answer:
116
Step-by-step explanation:
you can use variables
a+b=110
a+c=112
a+d=113
b+c=118
b+d=121
add up the weights and you get 574 kg (you need to find c+d)
3a+3b+2c+2d=574
a+b+c+d = 230 as given then you multiply by 3 so you can cancel out 3a and 3b and subtract 690-574 because we multiplied by 3
you are left with c+d=116
similar method to the answer previously