Progression Practice Test 1

Question : 7 of 23

Marks: +1, -0

Find the three numbers in AP whose sum is 33 and product is 1,155.

10, 14, 18
15, 10, 8
15, 11, 7
6, 10, 14
None of these

Solution:

Let the numbers be (a - d), a and (d + d). Then
(a - d) + a + (a + d) = 33
⇒ 3a = 33
⇒ a = 11
Now (a - d) (a) (a + d) = 1,155
(11 - d) (11) (11 + d) = 1,155

(11^2-d^2)=105

d^2=16

d=±4

∴ Numbers are 7, 11, 15 or 15, 11, 7

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