IIT JEE Practice Question and Answer

Q: A box contains 4 different black balls, 3 different red balls and 5 different blue balls. In how many ways can the balls be selected if every selection must have at least 1 black ball and one red ball ? 2579 0

  • 1
    24 - 1
    Correct
    Wrong
  • 2
    2425-1
    Correct
    Wrong
  • 3
    (24-1)(23-1)25
    Correct
    Wrong
  • 4
    None
    Correct
    Wrong
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Answer : 3. "(24-1)(23-1)25"
Explanation :

Answer: C) C Explanation: It is explicitly given that all the 4 black balls are different, all the 3 red balls are different and all the 5 blue balls are different. Hence this is a case where all are distinct objects.   Initially let's find out the number of ways in which we can select the black balls. Note that at least 1 black ball must be included in each selection.   Hence, we can select 1 black ball from 4 black ballsor 2 black balls from 4 black balls.or 3 black balls from 4 black balls.or 4 black balls from 4 black balls.   Hence, number of ways in which we can select the black balls   = 4C1 + 4C2 + 4C3 + 4C4= 24-1 ........(A)   Now let's find out the number of ways in which we can select the red balls. Note that at least 1 red ball must be included in each selection.   Hence, we can select 1 red ball from 3 red ballsor 2 red balls from 3 red ballsor 3 red balls from 3 red balls   Hence, number of ways in which we can select the red balls= 3C1 + 3C2 + 3C3=23-1........(B)   Hence, we can select 0 blue ball from 5 blue balls (i.e, do not select any blue ball. In this case, only black and red balls will be there)or 1 blue ball from 5 blue ballsor 2 blue balls from 5 blue ballsor 3 blue balls from 5 blue ballsor 4 blue balls from 5 blue ballsor 5 blue balls from 5 blue balls.   Hence, number of ways in which we can select the blue balls= 5C0 + 5C1 + 5C2 + … + 5C5= 25..............(C)   From (A), (B) and (C), required number of ways=  2524-123-1

Q: Size of the primary memory of a pc ranges between 2578 0

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    256 kb to 640 kb
    Correct
    Wrong
  • 2
    64 kb to 256 kb
    Correct
    Wrong
  • 3
    256 kb to 512 kb
    Correct
    Wrong
  • 4
    2 kb to 8 kb
    Correct
    Wrong
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Answer : 1. "256 kb to 640 kb"
Explanation :

Answer: A) 256 kb to 640 kb Explanation: Size of the primary memory of a PC ranges between 256 KB to 640 KB.

Q: The circumference of a circular base of Cylinder is 44 cm and its hight is 15 cm. Then the volume of the cylinder is? 2577 0

  • 1
    2759 cub. cm
    Correct
    Wrong
  • 2
    2247 cub. cm
    Correct
    Wrong
  • 3
    2614 cub. cm
    Correct
    Wrong
  • 4
    2311 cub. cm
    Correct
    Wrong
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Answer : 4. "2311 cub. cm"
Explanation :

Answer: D) 2311 cub. cm Explanation: Given Circumference of a circular base of a cylinder = 44 cm We know that Circumference of a circle = 2πr = 44⇒r = 22π Now given the height of a cylinder h = 15 cm Volume of a cylinder V = πr2h = π22π215 = 22 x 22 x 153.14 = 2311 cm3.

Q: If two fractions, each of which has a value between 0 and 1, are multiplied together, the product will be : 2577 0

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    always greater than either of the original fractions
    Correct
    Wrong
  • 2
    always less than either of the original fractions
    Correct
    Wrong
  • 3
    sometimes greater and sometimes less than either of the original fractions
    Correct
    Wrong
  • 4
    remains the same
    Correct
    Wrong
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Answer : 2. "always less than either of the original fractions"
Explanation :

Answer: B) always less than either of the original fractions Explanation: We can easily Answer this by taking some values.   The question states that the two fractions, each have values between 0 and 1.Let us say one of the fraction is 1/2 and the other fraction is 1/3 .The product of the two fractions is 1/2 x 1/3 = 1/6 . is lesser than both 1/2  and 1/3 .So, the correct answer is that the product is always less than either of the original fractions.

Q: Most important weather phenomena occur in the 2577 0

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    Troposphere
    Correct
    Wrong
  • 2
    Stratosphere
    Correct
    Wrong
  • 3
    Ionosphere
    Correct
    Wrong
  • 4
    Thermosphere
    Correct
    Wrong
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Answer : 4. "Thermosphere"
Explanation :

Answer: D) Thermosphere Explanation: Most important weather phenomena occur in the layer of Thermosphere. Most of the weather phenomenon occur in the layer of Troposphere.

Q: Assertive sentences examples list. 2575 0

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Answer :
Explanation :

An assertive sentence is a sentence that state, assert, or declare something. It means it is a simple statement making thing. As it declares something, is also called as Declarative sentence.       Examples of assertive sentence or statements ::   1. Anamika loves him very much.   2. He picks her daily.   3. Attitude is everything.   4. The sun sets in the west.   5. She likes roses.   6. He is a student.   7. Karthik planned a tour.   8. Peacock is a beautiful bird.   9. India is our country.   10. Joel want to be a doctor.

Q: The last two digits of 2151415? 2574 0

  • 1
    81
    Correct
    Wrong
  • 2
    61
    Correct
    Wrong
  • 3
    91
    Correct
    Wrong
  • 4
    51
    Correct
    Wrong
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Answer : 4. "51"
Explanation :

Answer: D) 51 Explanation: Unit digit of this expression is always 1 as the base ends with 1.  For the tenth place digit we need to multiply the digit in the tenth place of the base and unit digit of the power and take its unit digit. i.e, tenth place digit in 2151 is 5 and tenth place digit in power 415 is 1 And the units digit in the product of 5 x 1 = 5   Therefore, last two digits of 2151415 is 51.

Q: If a quarter kg of carrots costs 60 paise, how many paise will 200 gms cost ? 2573 0

  • 1
    78 paise
    Correct
    Wrong
  • 2
    48 paise
    Correct
    Wrong
  • 3
    54 paise
    Correct
    Wrong
  • 4
    62 paise
    Correct
    Wrong
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Answer : 2. "48 paise"
Explanation :

Answer: B) 48 paise Explanation: Quarter of Kg means 250 gm Less weight, less price (Direct Proportion) So, 250 : 200 :: 60 : x => x = 48 So 200 gm will cost 48 paise.

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