IIT JEE प्रश्न और उत्तर का अभ्यास करें
8प्र: K can build a wall in 30 days. L can demolish that wall in 60 days. If K and L work on alternate days, when will the wall be completed ? 2952 15b5cc6f8e4d2b4197774f081
5b5cc6f8e4d2b4197774f081- 1120 daysfalse
- 2119 daysfalse
- 3118 daysfalse
- 4117 daystrue
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उत्तर : 4. "117 days"
व्याख्या :
Answer: D) 117 days Explanation: K's work in a day(1st day) = 1/30L's work in a day(2nd day)= -1/60(demolishing)hence in 2 days, combined work= 1/30 - 1/60 =1/60since both works alternatively, K will work in odd days and L will work in even days.1/60 unit work is done in 2 days58/60 unit work will be done in 2 x 58 days = 116 daysRemaining work = 1-58/60 = 1/30Next day, it will be K's turn and K will finish the remaining 1/30 work.hence total days = 116 + 1 = 117.
प्र: Optimist is to cheerful as Pessimist is to 2951 05b5cc69ce4d2b4197774c855
5b5cc69ce4d2b4197774c855- 1Helpfulfalse
- 2Meanfalse
- 3Pettyfalse
- 4Gloomytrue
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उत्तर : 4. "Gloomy"
व्याख्या :
Answer: D) Gloomy Explanation: The given words are related in a way that, an optimist is a person whose outlook is cheerful. Similarly, a pessimist is a person whose outlook is gloomy. The answer is not (b) because a pessimist does not have to be mean. Options (c) and (a) are incorrect because neither words describe the outlook of a pessimist. Hence, Optimist is to cheerful as Pessimist is to Gloomy.
प्र: fifteen persons are sitting around a circular table facing the centre. What is the probability that three particular persons sit together ? 2950 05b5cc731e4d2b4197774f7dd
5b5cc731e4d2b4197774f7dd- 13/91true
- 22/73false
- 31/91false
- 43/73false
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उत्तर : 1. "3/91"
व्याख्या :
Answer: A) 3/91 Explanation: In a circle of n different persons, the total number of arrangements possible = (n - 1)!Total number of arrangements = n(S) = (15 – 1)! = 14 !Taking three persons as a unit, total persons = 13 (in 4 units)Therefore no. of ways for these 13 persons to around the circular table = (13 - 1)! = 12!In any given unit, 3 particular person can sit in 3!. Hence total number of ways that any three person can sit =n(E) = 12! X 3!Therefore P (E) = probability of three persons sitting together = n(E) / n(S) = 12! X 3 ! / 14!= 12!x3x2 / 14x13x12! = 6/14x13 = 3/91
प्र: The circumferences of two circles are 264 meters and 352 meters. Find the difference between the areas of the larger and the smaller circles ? 2947 05b5cc6dee4d2b4197774ea79
5b5cc6dee4d2b4197774ea79- 12413 sq.mfalse
- 21234 sq.mfalse
- 34312 sq.mtrue
- 42143 sq.mfalse
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उत्तर : 3. "4312 sq.m"
व्याख्या :
Answer: C) 4312 sq.m Explanation: Let the radii of the smaller and the larger circles be 's' m and 'l' m respectively. 2πs = 264 and 2πl = 352 s = 2642π and l = 3522π Difference between the areas =πl2-πs2 = π1762π2-1322π2 = 1762π-1322π = (176 - 132)(176 + 132) / π = (44 x 308) / (22/7) = 4312 sq.m
प्र: The gas predominantly responsible for global warming is 2947 05b5cc675e4d2b4197774c0fc
5b5cc675e4d2b4197774c0fc- 1Carbon monoxidefalse
- 2Nitrous oxidefalse
- 3Nitrogen peroxidefalse
- 4Carbondioxidetrue
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उत्तर : 4. "Carbondioxide"
व्याख्या :
Answer: D) Carbondioxide Explanation: 72% of the totally emitted greenhouse gases is carbon dioxide. Hence, Carbon dioxide (Co2) is predominantly responsible for Global warming.
प्र: A train moving at 2/3 rd of its normal speed reaches its destination 20 minutes late. Find the normal time taken ? 2945 05b5cc71ee4d2b4197774f57c
5b5cc71ee4d2b4197774f57c- 14/3 hrsfalse
- 22/3 hrstrue
- 33/2 hrsfalse
- 41/4 hrsfalse
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उत्तर : 2. "2/3 hrs"
व्याख्या :
Answer: B) 2/3 hrs Explanation: Let the original speed and time is S and Tthen distance = S x TNow the speed changes to 2/3S and T is T+20As the distance is sameS x T = 2/3Sx(T+20)solving this we get t = 40 minutes =40/60 = 2/3 hour
प्र: 96% of the population of a village is 23040. The total population of the village is ? 2945 05b5cc6e7e4d2b4197774ed92
5b5cc6e7e4d2b4197774ed92- 124000true
- 232256false
- 325478false
- 426587false
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उत्तर : 1. "24000"
व्याख्या :
Answer: A) 24000 Explanation: Let the total population be 'P' P x (96/100) = 23040 P = 240 * 100 P = 24000.
प्र: Which of the following metals forms an amalgam with other metals ? 2936 15b5cc6d9e4d2b4197774e86c
5b5cc6d9e4d2b4197774e86c- 1Mercurytrue
- 2Zincfalse
- 3Tinfalse
- 4Leadfalse
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उत्तर : 1. "Mercury"
व्याख्या :
Answer: A) Mercury Explanation: