IIT JEE Practice Question and Answer
8Q: Two dice are rolled simultaneously. Find the probability of getting the sum of numbers on the on the two faces divisible by 3 or 4? 1033 05b5cc6bbe4d2b4197774d811
5b5cc6bbe4d2b4197774d811- 13/7false
- 27/11false
- 35/9true
- 46/13false
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Answer : 3. "5/9"
Explanation :
Answer: C) 5/9 Explanation: Here n(S) = 6 x 6 = 36 E={(1,2),(1,5),(2,1),(2,4),(3,3),(3,6),(4,2),(4,5),(5,1),(5,4),(6,3) ,(6,6),(1,3),(2,2),(2,6),(3,1),(3,5), (4,4),(5,3),(6,2)} => n(E)=20 Required Probability n(P) = n(E)/n(S) = 20/36 = 5/9.
Q: A train travelling at 48 kmph crosses another train, having half its length and travelling in opposite direction at 42 kmph, in 12 sec. It also covers a bridge in 45 sec. Find the length of the bridge ? 1032 05b5cc6c4e4d2b4197774dcc3
5b5cc6c4e4d2b4197774dcc3- 1250 mtsfalse
- 2400 mtstrue
- 3320 mtsfalse
- 4390 mtsfalse
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Answer : 2. "400 mts"
Explanation :
Answer: B) 400 mts Explanation: Let the length of the 1st train = L mts Speed of 1st train = 48 kmph Now the length of the 2nd train = L/2 mts Speed of 2nd train = 42 kmph Let the length of the bridge = D mts Distance = L + L/2 = 3L/2 Relative speed = 48 + 42 = 90 kmph = 90 x 5/18 = 25 m/s(opposite) Time = 12 sec => 3L/2x25 = 12 => L = 200 mts Now it covers the bridge in 45 sec => distance = D + 200 Time = 45 sec Speed = 48 x5/18 = 40/3 m/s => D + 200/(40/3) = 45 => D = 600 - 200 = 400 mts Hence, the length of the bridge = 400 mts.
Q: A can do a work in 9 days, B can do a work in 7 days, C can do a work in 5 days. A works on the first day, B works on the second day and C on the third day respectively that is they work on alternate days. When will they finish the work ? 1032 05b5cc73de4d2b4197774f94d
5b5cc73de4d2b4197774f94d- 1[7 + (215/345)] daysfalse
- 2[6 + (11/215)] daysfalse
- 3[6 + (261/315)] daystrue
- 4[5 + (112/351)] daysfalse
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Answer : 3. "[6 + (261/315)] days"
Explanation :
Answer: C) [6 + (261/315)] days Explanation: After day 1, A finishes 1/9 of the work. After day 2, B finishes 1/7 more of the total work. (1/9) + (1/7) is finished. After day 3, C finishes 1/5 more of total work. Total finished is 143/315. So, after day 6, total work finished is 286/315. Now remaining work = 29 /315 On day 7, A will work again Work will be completed on day 7 when A is working. He must finish 29/315 of total remaining work. Since he takes 9 days to finish the total task, he will need 261/315 of the day. Total days required is 6 + (261/315) days.
Q: The compound interest on Rs. 8000 for 3 year at 10% p.a. is 1032 05b5cc6b9e4d2b4197774d6df
5b5cc6b9e4d2b4197774d6df- 12648true
- 22145false
- 32587false
- 42784false
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Answer : 1. "2648"
Explanation :
Answer: A) 2648 Explanation: 8000 × 33.1% = 2648
Q: In how many different ways could couples be picked from 6 men and 9 women ? 1031 05b5cc728e4d2b4197774f728
5b5cc728e4d2b4197774f728- 126false
- 254true
- 352false
- 428false
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Answer : 2. "54"
Explanation :
Answer: B) 54 Explanation: Number of mens = 8 Number of womens = 5 Different ways could couples be picked = C16× 9C1 = 9 x 6 = 54 ways.
Q: Which country has been ranked number one in pollution related deaths ? 1031 05b5cc6c0e4d2b4197774db19
5b5cc6c0e4d2b4197774db19- 1Australiafalse
- 2Indonesiafalse
- 3Indiatrue
- 4Japanfalse
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Answer : 3. "India"
Explanation :
Answer: C) India Explanation:
Q: What is the four-digit number in which the first digit is 1/3 of the second,the third is the sum of the first and second, and the last is three times the second ? 1030 05b5cc71be4d2b4197774f558
5b5cc71be4d2b4197774f558- Show Answer
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Answer :
Explanation :
It is given that the first digit is 1/3 of the second. There are 3 such possibilities 1)1 and 32)2 and 63)3 and 9 Now, the third digit is the sum of the first and second digits.1)1 + 3 = 4 2)2 + 6 = 83)3 + 9 = 12It is clear that option 3 is not possible. So we are left with only two options. Also, the last digit is three times the second, which rules out the second option. Hence, the answer is 1349.
Q: Which of the following is the strongest acid? 1030 05b5cc6b7e4d2b4197774d5ec
5b5cc6b7e4d2b4197774d5ec- 1ClCH2COOHfalse
- 2BrCH2COOHfalse
- 3FCH2COOHtrue
- 4ICH2COOHfalse
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Answer : 3. "FCH2COOH"
Explanation :
Answer: C) FCH2COOH Explanation: FCH2COOH is the strongest acid out of all .Since the electron withdrawing inductive effect (-I effect) of the halogens decreases in the order F>Cl> Br> I , therefore the acidic strength of the α- halo acids decreases in the same order. FCH2COOH > ClCH2COOH > BrCH2COOH > ICH2COOH.