Question

The average weight of 21 boys was recorded
as 64 kgs. If the weight of the teacher was added,
the average increased by 1 kg. What was the
teacher's weight?
(A) 98 kgs
(B) 72 kgs
(C) 64 kgs
(D) 86 kgs​

Answer 1

Answer:

So, average weight of 21 boys is 64 kg.

So sum of their weight will be 64×21=1344.

Now, let the teacher's weight be x.

So, average=Sum of no. /no.

1344+x/22=65

1344+x=65×22

1344+x=1430

x=1430-1344=86

Ans d) 86kg

Answer 2

Concept

The average is also referred to as the arithmetic mean, which is calculated by dividing the total number of numbers in a collection by the total number of numbers in the collection. The ratio between the sum of all provided observations and the total number of observations is what is meant by the term "average."

Given

average weight of 21 boys = 64 kgs

after adding the weight of the teacher the average increased  = 1 kg

Find

the weight of the teacher.

Solution

given,

average weight of 21 boys = 64 kgs

therefore, total weight of 21 boys

= 65 × 21

= 1344 kg

The average weight increased by 1 kg after the teacher's weight was added.

Total weight of teacher and 21 boys.

= 65 × 22

= 1430 kg

so weight of teacher

= 1430 ₋ 1344

= 86 kg

so, we determine that the teacher is 86 kg in weight.

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