Of the four numbers whose average is 91, the first is 3/10 times the sum of other three. The first number is :
1). 126
2). 56
3). 168
4). 84
Let the first number be x.
x = (3/10) × (sum of other three sides)
Therefore, sum of other three sides = (10/3) × x
Average = Sum of four sides/4
Average = (x + sum of other three sides)/4
Therefore, Average = (x + 10x/3)/4
Since average = 91
91 = (13x/3)/4
x = (91 × 12)/13
x = 84
Therefore, the first number is 84.