Question

Find the 1st of AP whose 8th and 12th terms are respectively 60 and 80.

Answer 1

Answer:

Correct option (c) 25

Step-by-step explanation:

Since the 8th and the 12th terms of the AP are given as 60 and 80, respectively, the difference between the two terms would equal 4 times the common difference. Thus we get 4d = 80 − 60 = 20. This gives us d = 5. Also, the 8th term in the AP is represented by a + 7d, we get: a + 7d = 60 → a + 7 × 5 = 60→ a = 25.