3 के चार क्रमागत गुणज का योग 78 है। इनमें से सबसे बड़ी संख्या है:

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  1. 18
  2. 27
  3. 24
  4. 21

Answer (Detailed Solution Below)

Option 3 : 24
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दिया गया है:

3 के चार क्रमागत गुणज का योग = 78

गणना:

मान लीजिये कि 3 का पहला गुणज = 3a 

इसी प्रकार, 3 का दूसरा गुणज = 3(a + 1) 

⇒ 3 का तीसरा गुणज = 3(a + 2) 

⇒ 3 का चौथा गुणज = 3(a + 3) 

3a +3(a + 1) + 3(a + 2) + 3(a + 3) = 78

⇒ 3a + 3a + 3 + 3a + 6 + 3a + 9 = 78

⇒ 12a + 18 = 78

⇒ 12a = 78 - 18 = 60 

⇒ a = 60/12 = 5  

∴ 3 का सबसे बड़ा गुणज = 3(a + 3) = 3 × (5 + 3) = 24

Shortcut Trick गणना:

3 के क्रमागत 4 गुणजों का औसत = 78/4 = 19.5

तो, संख्या 18 और 21 होनी चाहिए।

तो श्रृंखला होगी

15, 18, 21, 24

∴ सबसे बड़ा गुणज 24 है।

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