IIT JEE प्रश्न और उत्तर का अभ्यास करें

प्र: Which is not associated with areas of karst topography? 1814 0

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    flowing rivers
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  • 2
    sinkholes
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  • 3
    sinking streams
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  • 4
    caverns
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उत्तर : 1. "flowing rivers"
व्याख्या :

Answer: A) flowing rivers Explanation: A karst topography is that which composes of limestone and its associated features and structures. Karst topography and caves develop in limestone rocks due to their solubility in dilute acidic groundwater. The solubility of limestone in water and weak acid solutions leads to karst landscapes.   Flowing rivers, can be found in areas away from karst topography.

प्र: A bag contains 4 red and 3 black balls. A second bag contains 2 red and 4 black balls. One bag is selected at random. From the selected bag, one ball is drawn. Find the probability that the ball drawn is red. 1813 0

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    23/42
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  • 2
    19/42
    सही
    गलत
  • 3
    7/32
    सही
    गलत
  • 4
    16/39
    सही
    गलत
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उत्तर : 2. "19/42"
व्याख्या :

Answer: B) 19/42 Explanation: A red ball can be drawn in two mutually exclusive ways  (i) Selecting bag I and then drawing a red ball from it.   (ii) Selecting bag II and then drawing a red ball from it.   Let E1, E2 and A denote the events defined as follows: E1 = selecting bag I, E2 = selecting bag II A = drawing a red ball Since one of the two bags is selected randomly, therefore  P(E1) = 1/2  and  P(E2) = 1/2 Now, PAE1 = Probability of drawing a red ball when the first bag has been selected = 4/7   PAE2  = Probability of drawing a red ball when the second bag has been selected = 2/6  Using the law of total probability, we have   P(red ball) = P(A) = PE1×PAE1+PE2×PAE2                              = 12×47+12×26=1942

प्र: What percent of a day is 3 hours? 1812 0

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    14.9%
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  • 2
    12.5%
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  • 3
    15.6%%
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  • 4
    11.4%
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उत्तर : 2. "12.5%"
व्याख्या :

Answer: B) 12.5% Explanation: Let p% of a day is 3 hrs. We know that a day has 24 hrs. => p x 24/100 = 3 => p = 300/24 => p = 12.5%   Hence, 3 hrs is 12.5% of a day.

प्र: There are 41 students in a class, number of girls is one more than number of guys. we need to form a team of four students. all four in the team cannot be from same gender. number of girls and guys in the team should NOT be equal. How many ways can such a team be made ? 1811 0

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    49450
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  • 2
    50540
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  • 3
    46587
    सही
    गलत
  • 4
    52487
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    गलत
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उत्तर : 2. "50540"
व्याख्या :

Answer: B) 50540 Explanation: Given G + B= 41 and B = G-1 Hence, G = 21 and B = 20Now we have 2 options, 1G and 3M (or) 3G and 1M(2G and 2M or 0G and 4M or 4G and oM are not allowed),   Total : C121×C320+C321×C120= 50540 ways.

प्र: The first attempt made to enumerate the population of India was done in which year ? 1810 0

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    1884
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  • 2
    1896
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  • 3
    1921
    सही
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  • 4
    1872
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उत्तर : 4. "1872"
व्याख्या :

Answer: D) 1872 Explanation:

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उत्तर : 2. "1/6"
व्याख्या :

Answer: B) 1/6 Explanation: Total work is given by L.C.M of 72, 48, 36 Total work = 144 units Efficieny of A = 144/72 = 2 units/day Efficieny of B = 144/48 = 3 units/day Efficieny of C = 144/36 = 4 units/day   According to the given data, 2 x p/2 + 3 x p/2 + 2 x (p+6)/3 + 3 x (p+6)/3 + 4 x (p+6)/3 = 144 x (100 - 125/3) x 1/100 3p + 4.5p + 2p + 3p + 4p = 84 x 3 - 54 p = 198/16.5 p = 12 days.   Now, efficency of D = (144 x 125/3 x 1/100)/10 = 6 unit/day (C+D) in p days = (4 + 6) x 12 = 120 unit Remained part of work = (144-120)/144 = 1/6.

प्र: 8 S on a SS means? 1810 0

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व्याख्या :

8 S on SS means 8 Sides on a Stop Sign. This is one type of Letter Equations which are well known phrases or facts where the key words have been replaced with the first letter of that word. These are often in the form of an equation, which contain a number, an = sign and the rest of the obscured phrase or fact.   Some more of them are :: 90 D in a RA 26 L of the A  12 S of the Z.

प्र: 3 is what percent of 5? 1810 0

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    45%
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  • 2
    60%
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  • 3
    72%
    सही
    गलत
  • 4
    80%
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उत्तर : 2. "60%"
व्याख्या :

Answer: B) 60% Explanation: Here it is asked that 3 is what percent of 5 Let 3 is K percent of 5. => K x 5/100 = 3 => K = 300/5 = 60   Hence, 3 is 60% of 5.

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