IIT JEE Practice Question and Answer
8Q: fifteen persons are sitting around a circular table facing the centre. What is the probability that three particular persons sit together ? 3645 05b5cc731e4d2b4197774f7dd
5b5cc731e4d2b4197774f7dd- 13/91true
- 22/73false
- 31/91false
- 43/73false
- Show AnswerHide Answer
- Workspace
- SingleChoice
Answer : 1. "3/91"
Explanation :
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
Q: If 34 men completed 2/5th of a work in 8 days working 9 hours a day. How many more man should be engaged to finish the rest of the work in 6 days working 9 hours a day ? 3644 05b5cc6d9e4d2b4197774e807
5b5cc6d9e4d2b4197774e807- 1101 menfalse
- 2112 menfalse
- 3102 mentrue
- 4120 menfalse
- Show AnswerHide Answer
- Workspace
- SingleChoice
Answer : 3. "102 men"
Explanation :
Answer: C) 102 men Explanation: From the above formula i.e (m1 x t1/w1) = (m2 x t2/w2) so, [(34 x 8 x 9)/(2/5)] = [(M x 6 x 9)/(3/5)] so, M = 136 men Number of men to be added to finish the work = 136-34 = 102 men.
Q: A periscope works by the principle of 3641 05b5cc678e4d2b4197774c183
5b5cc678e4d2b4197774c183- 1Total internal reflectiontrue
- 2Refractionfalse
- 3Diffractionfalse
- 4Reflection & Refractionfalse
- Show AnswerHide Answer
- Workspace
- SingleChoice
Answer : 1. "Total internal reflection"
Explanation :
Answer: A) Total internal reflection Explanation: A periscope is an optical instrument that uses a system of prisms, lenses, or mirrors to reflect images through a tube. Light from a distant object strikes the top mirror and is then reflected at an angle of 90 degrees down the periscope tube. At the bottom of the periscope, the light strikes another mirror and is then reflected into the viewer’s eye. Hence, A periscope works by the principle of Total internal reflection.
Q: In what way does ocean water move globally? 3641 05b5cc672e4d2b4197774c082
5b5cc672e4d2b4197774c082- 1Along cold water currents from the equator to the poles.false
- 2Along warm water currents from the warmer regions to colder regionsfalse
- 3Along warm water currents from the equator to the polestrue
- 4None of the abovefalse
- Show AnswerHide Answer
- Workspace
- SingleChoice
Answer : 3. "Along warm water currents from the equator to the poles"
Explanation :
Answer: C) Along warm water currents from the equator to the poles Explanation:
Q: The 1911 Chinese revolution ended the rule of the 3636 05b5cc68be4d2b4197774c365
5b5cc68be4d2b4197774c365- 1Ming dynastyfalse
- 2Mongolians dynastyfalse
- 3Song dynastyfalse
- 4Manchus dynastytrue
- Show AnswerHide Answer
- Workspace
- SingleChoice
Answer : 4. "Manchus dynasty"
Explanation :
Answer: D) Manchus dynasty Explanation: It was the Qing Dynasty, who was a Manchu Dynasty whose rule ended in 1911 Chinese revolution.
Q: Simplify the following equation 55.55 + 155 + 15.55 + 0.5 + 0.05 = ? 3635 05b5cc604e4d2b4197774b4fd
5b5cc604e4d2b4197774b4fd- 1226.65true
- 2196.55false
- 3202.35false
- 4216.66false
- Show AnswerHide Answer
- Workspace
- SingleChoice
Answer : 1. "226.65"
Explanation :
Answer: A) 226.65 Explanation: 55.55 + 155 + 15.55 + 0.5 + 0.05 = ? 55.55 155.00 15.55 0.5 0.05 _______ 226.65 _______ Hence, the value of the given equation 55.55 + 155 + 15.55 + 0.5 + 0.05 = 226.65.
Q: In a certain code ARCHIVE is written as DSBGFWJ. How is SYSTEMS is written in that code ? 3633 05b5cc75ee4d2b4197774fcf8
5b5cc75ee4d2b4197774fcf8- 1TZTSTUNfalse
- 2TZTSTNFtrue
- 3TZTUTNFfalse
- 4TZTNTFSfalse
- Show AnswerHide Answer
- Workspace
- SingleChoice
Answer : 2. "TZTSTNF"
Explanation :
Answer: B) TZTSTNF Explanation: ARC -> CRA ->(+1) DSB H -> H ->(-1) GIVE -> EVI ->(+1) FWJ Similarly, SYS -> SYS ->(+1) TZT T -> T ->(-1) SEMS -> SME ->(+1) TNF
Q: Which of the following is not purely output device? 3632 15b5cc688e4d2b4197774c32c
5b5cc688e4d2b4197774c32c- 1Printerfalse
- 2Speakerfalse
- 3Plotterfalse
- 4Screentrue
- Show AnswerHide Answer
- Workspace
- SingleChoice
Answer : 4. "Screen"
Explanation :
Answer: D) Screen Explanation: A touch screen is the only device which works as both an input and an output device among the given options. You view the options available to you on the screen (output) and you then use your finger to touch the option that you have chosen (input). Hence, Screen is not purely output device.

