Total Questions: 100
4 1/2+3 3 1/3 +? + 2 1/3 = 13 2/5
12, 51, 18, 21, 99.
12, 15, 18, ..........99
a = 12, d = 15 - 12 = 3
99 = 12 + (n-1) 3
⇒ 87/3 = n-1
⇒ n = 30
Required sum
= n/2 [ 2a + ( n-1) d ]
= 30/2 [ 2 x 12 + (30 - 1 ) x 3 ]
= 15 [ 24 + 87 ]
= 15 x 111 = 1665
According to question,
x x 15 + (80 - x) x 5 = 500
⇒ 15x + 400 - 5x = 500
⇒ 10x = 100
x = 10km