IIT JEE Practice Question and Answer

Q: How many zeros are there from 1 to 10000 ? 3352 0

  • 1
    2893
    Correct
    Wrong
  • 2
    4528
    Correct
    Wrong
  • 3
    6587
    Correct
    Wrong
  • 4
    4875
    Correct
    Wrong
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Answer : 1. "2893"
Explanation :

Answer: A) 2893 Explanation: For solving this problem first we would break the whole range in 5 sections 1) From 1 to 9Total number of zero in this range = 0 2) From 10 to 99Total possibilities = 9*1 = 9 ( here 9 is used for the possibilities of a non zero integer) 3) From 100 to 999 - three type of numbers are there in this range a) x00 b) x0x c) xx0 (here x represents a non zero number)Total possibilities for x00 = 9*1*1 = 9, hence total zeros = 9*2 = 18for x0x = 9*1*9 = 81, hence total zeros = 81similarly for xx0 = 81 total zeros in three digit numbers = 18 + 81 +81 = 180 4) From 1000 to 9999 - seven type of numbers are there in this rangea)x000 b)xx00 c)x0x0 d)x00x e)xxx0 f)xx0x g)x0xxTotal possibilities for x000 = 9*1*1*1 = 9, hence total zeros = 9*3 = 27 for xx00 = 9*9*1*1 = 81, hence total zeros = 81*2 = 162 for x0x0 = 9*1*9*1 = 81, hence total zeros = 81*2 = 162for x00x = 9*1*1*9 = 81, hence total zeros = 81*2 = 162 for xxx0 = 9*9*9*1 = 729, hence total zeros = 729*1 = 729for xx0x = 9*9*1*9 = 729, hence total zeros = 729*1 = 729for x0xx = 9*1*9*9 = 729, hence total zeros = 729*1 = 729total zeros in four digit numbers = 27 + 3*162 + 3*729 = 2700thus total zeros will be 0+9+180+2700+4 (last 4 is for 4 zeros of 10000)= 2893

Q: If 10 men take 15 days to complete a work. In how many days will 37 men complete the work? 3352 0

  • 1
    3 days
    Correct
    Wrong
  • 2
    4 days
    Correct
    Wrong
  • 3
    5 days
    Correct
    Wrong
  • 4
    6 days
    Correct
    Wrong
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Answer : 2. "4 days"
Explanation :

Answer: B) 4 days Explanation: Given 10 men take 15 days to complete a work => Total mandays = 15 x 10 = 150 Let the work be 150 mandays. => Now 37 men can do 150 mandays in 150/37 =~ 4 days

Q: What Does My Name Mean, If my Mother is a Mathematician, and my Father is a Chemist. And they gave a Code to My Name as "Iron59". Crack my Name? 3350 0

  • 1
    Elix
    Correct
    Wrong
  • 2
    Alex
    Correct
    Wrong
  • 3
    Selix
    Correct
    Wrong
  • 4
    Felix
    Correct
    Wrong
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Answer : 4. "Felix"
Explanation :

Answer: D) Felix Explanation: Here my name "Iron59" means Felix. Since my father is a chemist he gave code Iron for Fe as chemical symbol for Iron is Fe and my mother is a mathematician she gave 59 for Lix as Roman word for 59 is Lix.   Hence my name is FELIX.

Q: A bird lover was asked how many birds he had in the basket. He replied that there were all parrots but six, all pigeons but six, and all koel but six. How many birds he had in the basket in all ? 3349 0

  • 1
    8
    Correct
    Wrong
  • 2
    18
    Correct
    Wrong
  • 3
    9
    Correct
    Wrong
  • 4
    10
    Correct
    Wrong
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Answer : 3. "9"
Explanation :

Answer: C) 9 Explanation: There were all parrots but six means that six birds were not parrots but only pigeons and koels. Similarly, number of parrots + number of koels = 6 and number of parrots + number of pigeons = 6. This is possible when there are 3 parrots, 3 pigeons and 3 koels i.e. 9 birds in all.

Q: When combining with nonmetallic atoms, metallic atoms generally will 3347 0

  • 1
    Lose electrons and forms cations
    Correct
    Wrong
  • 2
    Gain electrons and forms anions
    Correct
    Wrong
  • 3
    Lose electrons and forms anions
    Correct
    Wrong
  • 4
    Gain electrons and forms cations
    Correct
    Wrong
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Answer : 1. "Lose electrons and forms cations"
Explanation :

Answer: A) Lose electrons and forms cations Explanation: When combining with nonmetallic atoms, metallic atoms generally will Lose electrons and forms cations.   As the ionization energy of te metals are very low, so they can easily lose electrons and form positively charged ion called cations.

Q: A merchant buys two items for Rs. 7500. One item he sells at a profit of 16% and the other item at 14% loss. In the deal, the merchant makes neither any profit nor any loss. What is the difference between the selling price of both the items? 3347 0

  • 1
    Rs. 620
    Correct
    Wrong
  • 2
    Rs. 654
    Correct
    Wrong
  • 3
    Rs. 725
    Correct
    Wrong
  • 4
    Rs. 747
    Correct
    Wrong
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Answer : 1. "Rs. 620"
Explanation :

Answer: A) Rs. 620 Explanation: Let the C.P of one item is Rs. P and that of other is Rs. (7500 - P) According to the data given C.P = S.P => Px(116/100) + (7500-P)x(86/100) = 7500 => 30P = 105000 => P = 3500 Required difference between selling prices = Rs. [(3500/100) x 116] - [(4000/100) x 86] = 4060-3440 = Rs. 620

Q: The largest component of National Income in India is ____ ? 3341 0

  • 1
    Service Sector
    Correct
    Wrong
  • 2
    Industrial Sector
    Correct
    Wrong
  • 3
    Agriculture Sector
    Correct
    Wrong
  • 4
    Trade Sector
    Correct
    Wrong
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Answer : 1. "Service Sector"
Explanation :

Answer: A) Service Sector Explanation: The  largest component of National income is service sector.

Q: The average age of a couple and their son was 40 years, the son got married and a child was born just two years after their marriage. When child turned to 10 years, then the average age of the family becomes 38 years. What was the age of the daughter in law at the time of marriage ? 3340 0

  • 1
    12 years
    Correct
    Wrong
  • 2
    10 years
    Correct
    Wrong
  • 3
    14 years
    Correct
    Wrong
  • 4
    13 years
    Correct
    Wrong
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Answer : 1. "12 years"
Explanation :

Answer: A) 12 years Explanation: Given the average age of couple and their son = 40 => Sum of age (H +W +S) = 40×3 Let the age of daughter in law at the time of marriage = D years Now after 10 years, (H + S +W) + 3×12 + D +12 + 10 = 38×5 178 + D = 190 D = 190 -178 = 12 years

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