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| When a student weighing 45 kgs left a class, the average weight of the remaining 59 students increased by 200g. What is the average weight of the remaining 59 students? |
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Let the average weight of the 59 students be A. Therefore, the total weight of the 59 of them will be 59A.
When the weight of the student who left is added, the total weight of the class = 59A + 45
When this student is also included, the average weight decreases by 0.2 kgs.
(59A + 45) / 60 = A – 0.2
=> 59A + 45 = 60A – 12
=> 45 + 12 = 60A – 59A
=> A = 57.
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| S = { 1,3,5,7……100 elements}. How many ways are there to choose exactly 6 elements from S such that their sum is 51? |
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0 ways, because the sum of 6 odd numbers can never be odd.
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In the fig shown, if CP=BP and x=120, then y=
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y = 60. In triangle PBC, Angle C = 180-120= 60. Angle C= Angle B (angles opposite equal sides are equal). Therefore Angle B =60. Third angle has to be 180-(60+60) = 60.
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| Letters A to I is categorized into 4 groups. Assume the font we used here is Arial. Which group does the letter J belong to? Which group does the letter O belong to?
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All the letters on the first row are not symmetrical. All the letters on the second row are symmetrical for the top and bottom. All the letters on the third row are symmetrical for the left and right. All the letters on the last row are completely symmetrical. Therefore, J should go to the first row. O should go to the last row.
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| There are 2 brothers among a group of 20 persons. In how many ways can the group be arranged around a circle so that there is exactly one person between the two brothers?
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18 people can be arranged around a circle in 17! ways. There are exactly 18 places where the two brothers can be arranged. The brothers can be arranged in 2! ways.Therefore, the total number of ways 17! * 2 * 18 = 2 * 18!
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