Solution -
Let,
Four numbers are in proportion = a : b :: c : d
The sum of the squares of the four numbers = 50
a²+ b² + c² + d²= 50
The ratio of first two terms = 1:3
a : b = 1 : 3
a = 1
b = 3
The sum of the mean = 5
b + c = 5
c = 5 - b
c = 5 - 3
c = 2
Now,
a : b = c : d
1 : 3 = 2 : d
1/3 = 2/d
d = 3*2
d = 6
Now,
The average of the four numbers = Sum of value / Total no. of value
The average of the four numbers = (1 + 3 + 2 + 6) / 4
The average of the four numbers = 12/4
The average of the four numbers = 3
Hence,
The correct answer is option (b) 3.
Download App for Free PDF Download
GovtVacancy.Net Android App: Download |