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प्र: Which two method you need to implement for key Object in HashMap ? 1280 0

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उत्तर :
व्याख्या :

In order to use any object as Key in HashMap, it must implements equals and hashcode method in Java.

प्र: What is immutable object? Can you write immutable object ? 1535 0

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उत्तर :
व्याख्या :

Immutable classes are Java classes whose objects can not be modified once created. Any modification in Immutable object result in new object. For example is String is immutable in Java. Mostly Immutable are also final in Java, in order to prevent sub class from overriding methods in Java which can compromise Immutability. You can achieve same functionality by making member as non final but private and not modifying them except in constructor.

प्र: The circumferences of two circles are 264 meters and 352 meters. Find the difference between the areas of the larger and the smaller circles  ? 3117 0

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    2413 sq.m
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    1234 sq.m
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    4312 sq.m
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    2143 sq.m
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उत्तर : 3. "4312 sq.m"
व्याख्या :

Answer: C) 4312 sq.m Explanation: Let the radii of the smaller and the larger circles be 's' m and 'l' m respectively.    2πs = 264 and 2πl = 352      s = 2642π and l = 3522π    Difference between the areas =πl2-πs2      = π1762π2-1322π2    = 1762π-1322π     = (176 - 132)(176 + 132) / π     = (44 x 308) / (22/7) = 4312 sq.m

प्र: The compound interest earned by Sunil on a certain amount at the end of two years at the rate of 8% p.a. was Rs.2828.80. Find the total amount that Sunil got back at the end of two years in the form of principal plus interest earned  ? 2176 0

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    Rs. 11828.80
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    Rs. 19828.80
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  • 3
    Rs. 9828.80
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  • 4
    Rs. 19328.80
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उत्तर : 2. "Rs. 19828.80"
व्याख्या :

Answer: B) Rs. 19828.80 Explanation: Let the sum be Rs. P P{ 1+81002- 1 } = 2828.80   It is in the form of  a2-b2 = a+ba-b   P(8/100)(2 + 8/100) = 2828.80   P = 2828.80 / (0.08)(2.08)   = 1360/0.08 = 17000   Principal + Interest = Rs. 19828.80

प्र: Rifath Sharook has designed the world’s lightest satellite “KalamSat”. He hails from which country  ? 1272 0

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    Russia
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    Pakistan
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    Dubai
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  • 4
    India
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उत्तर : 4. "India"
व्याख्या :

Answer: D) India Explanation: Indian teen Rifath Sharook from Tamil Nadu has designed the world’s lightest & smallest satellite named “KalamSat”. The satellite weighs only 64 grams and will be launched by NASA on June 21, 2017. With this, he will become the first Indian student to have his experiment launched by NASA. The main role of the satellite will be to demonstrate the performance of 3-D printed carbon fibre. The satellite has been designed in a way which will have a 240-minute mission in space and will operate for 12 minutes in a micro-gravity environment of space.

प्र: When I went back to my hometown three years ago, I found that a lot of changes ______. 5006 0

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    were taken place
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    are taken place
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    had taken place
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    have taken place
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उत्तर : 3. "had taken place"
व्याख्या :

Answer: C) had taken place Explanation: Since he is telling about the thing that had happened in past.

प्र: There are 100 students in 3 sections A, B and C of a class. The average marks of all the three sections was 84. The average of B and C was 87.5 and the average marks of students in A section was : 4167 0

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    20
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    35
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    54
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    40
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उत्तर : 1. "20"
व्याख्या :

Answer: A) 20 Explanation: Numbers of students in section A = x ∴ Numbers of students in section B and C = (100 – x) ∴ x 70 + (100 – x) 87.5 = 84 100 => 70x + 87.5 100 – 87.5x = 8400 => 8750 – 17.5x = 8400 => 17.5x = 8750 – 8400 => x = 20.

प्र: The arithmetic mean of the following numbers 1, 2, 2, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6 and 7, 7, 7, 7, 7, 7, 7 is   ? 2265 0

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    6
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    9
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    7
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    5
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उत्तर : 4. "5"
व्याख्या :

Answer: D) 5 Explanation: Arithmatic mean = sum/members  => (1x1 + 2x2 + 3x3 + 4x4 + 5x5 + 6x6 + 7x7) / (1 + 2 + 3 + 4 + 5 + 6 + 7) => 140/28 = 5

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