Four boys weighed themselves in different pairs and alone. The weights of the pairs were 110 kg, 112 kg, 113 kg, 118 kg, 121 kg,

Question

2 years ago

15

and the weight of one pair was lost. The total weight of the four boys was 230 kg. What was the lost weight?

2 answers:

brilliants [131] · Answer 1 · 2022-12-02T16:09:03+03:00

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;

$_nC_r = \dfrac{n!}{r! \cdot (n - r)!}$

Which gives;

$_4C_2 = \dfrac{4!}{2! \cdot (4 - 2)!} = 6$

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

Learn more here:

mina [271] · Answer 2 · 2022-12-02T17:29:32+03:00

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