Question

Among a 3 digit number, the first is 5 times the third number, and the second
number is 2 times the third number. If the average of three numbers is 80, then
what is the difference between the first and the third number?*
30
O
120
150
80
O None of these​

Answer 1

Answer:

The difference between the first and the third number is 120.

Step-by-step explanation:

Let the 3 numbers be A, B and C.

Now, according to the Question,

A = 5 × C

A = 5C ---- 1

Similarly,

B = 2C

Also,

Average = (Sum of observations ÷ Number of observations)

80 = (A + B + C)/3

A + B + C = 80 × 3

A + B + C = 240

From eq.1 and eq.2 we get,

(5C) + (2C) + C = 240

5C + 2C + C = 240

8C = 240

C = 240/8

C = 30

So,

A = 5(30) = 150

B = 2(30) = 60

Now, we must find,

A - C = 150 - 30 = 120

Hence,

The difference between the first and the third number is 120.

Hope it helped and believing you understood it....All the best