Direction : Solve the given series and answer the following questions. Series:…
2024
Direction : Solve the given series and answer the following questions.
Series: a + 15, a+ 16.2, a+18.6, _____, _______, M
Note: (i) x and y are prime number less than 10. (y>x)
(ii) xy = a
(iii) 2a = 10y.
Find the value of M.
- A.
9y + x
- B.
12x + 8
- C.
2a - 2
- D.
All (a), (b) & (c)
- E.
None of the above
Attempted by 2 students.
Show answer & explanation
Correct answer: D
From 2a = 10y, a = 5y. Since xy = a, xy = 5y, so x = 5.
With y > x and both prime numbers less than 10, y = 7. Hence a = 35.
The series terms are a+15, a+16.2, a+18.6, a+22.2, a+27.0, and M.
The differences increase by 1.2 each time: 1.2, 2.4, 3.6, 4.8, 6.0.
So M = a + 33 = 35 + 33 = 68.
Now 9y + x = 9(7) + 5 = 68, 12x + 8 = 12(5) + 8 = 68, and 2a - 2 = 2(35) - 2 = 68. Therefore all three are correct.