Question

step by step answer hona ​

Answer 1

Answer:

The fourth number is 2

Step-by-step explanation:

Let first number = a

Second number = b

Third number = c

Fourth number = d

According to question-

The average to first three numbers is equal to 3 times of fourth number

i.e average of a, b, c =3d

Average of a, b, c = $\dfrac{a+b+c}{3}$

$\dfrac{a+b+c}{3}=3d$          -------------- 1

Given that-

Average of all numbers = 5

$\dfrac{a+b+c+d}{4} = 5$

a + b + c + d = 5 × 4

a + b + c + d = 20

a + b + c = 20 - d

Put a + b + c = 20 - d in equation 1, we get-

$\dfrac{a+b+c}{3} = 3d$

$\dfrac{20-d}{3}=3d$

20 -d = 3 × 3d

20 - d = 9d

20 = 9d + d

20 = 10d

$d = \dfrac{20}{10}$

d = 2

Hence the fourth number is 2