Q173
ArithmeticNumber Series & Progressions
The 5th and 11th term of an A.P. are 41 and 20 respectively. The first term is
- a.45
- b.65
- c.35
- d.55
Answer: (D) 55
From a + 4d = 41 and a + 10d = 20, 6d = −21 so d = −3·5. Then a = 41 − 4 × (−3·5) = 41 + 14 = 55. 45 and 35 come from using the wrong number of steps or the wrong sign of d.