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maths problem (Discussion)

Gurudev said – Sat, 27 Jun 2009 18:13:55 -0000 ( Edit Link )

1. Given the mean of 18 numbers as ‘m’ and standard Deviation as ‘s’. If two numbers among 18 numbers are equal to m, then Col A: Standard Deviation of rest 16 numbers Col B: s

2. In a company, there are 54 members. If Wednesday has more number of birthdays than on any other day of the week, then Col A: The least number of birthdays on Wednesday Col B: 8

3.. If w > 0 and z > 0, then Col A: w^{4 + z}3 Col B: w^{2 + z}

4.If ‘n’ is positive integer, then Col A: The unit place of 〖156〗n Col B: The unit place of 〖165〗ⁿ

5.Given that there are ‘x’ boxes and the balls are arranged in such a way that no ball is left. If the number of boxes is reduced by 3 and if 12 balls are arranged in them, then 5 balls are left behind, what is the original number of boxes ‘x’?

6. If the sum of a list of 12 distinct positive even numbers is 156, then Col A: Range of the twelve numbers Col B: 20

7Given a parabola y = x2 – 3 which intersects y-axis at one point. If a point in xy-plane is P (2, k), then find the distance between the point P and the intersecting point on y-axis? Ans: 2 sqrt(5)

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amanpreet055 said – Sun, 28 Jun 2009 05:37:39 -0000 ( Flag Edit Mark / Unmark Best Link )

for the 1st question the answer is A…. that is bcz….. standard deviation has the formula where the mean of squares of differences of all the 18 no. from mean is taken… so for 18 no.. denominator iis 18…. for 16 no… denominator is 16 … column a is big
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amanpreet055 said – Sun, 28 Jun 2009 05:46:41 -0000 ( Flag Edit Mark / Unmark Best Link )

for 2 question the answer shud be A.. that is when we equally divide the birthdays in a week… 7×7= 49… 5 b days left… now as you have to put 2 more bdays in wed because it has more bdays than any other day…...so rest days get either 7 bdays or 8… but wed shuld have atleast 9…(7+2)
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Chortle16 said – Sun, 28 Jun 2009 13:46:57 -0000 ( Flag Edit Mark / Unmark Best Link )

Answer 4: col A: 156^{n col B: 165}n; given n is a positive integer.

if u consider “n” to be 2 or any other integer…..........the units place remains the same for both 156 n 165. 6 to power of any positive integer would result in 6. Similarly, 5 to the power of any integer would be 5. The answer would be A since 6 is greater than 5.
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Chortle16 said – Sun, 28 Jun 2009 14:38:54 -0000 ( Flag Edit Mark / Unmark Best Link )

6. 12 distinct positive even numbers…..........sum is 156. Add the even numbers until u get a sum of 156….......it’ll come up to 24. so the range is from 2 to 24. It can be greater or lesser than 20. So the answer is D.

7. y = x^{2. – 3 P=(2,k) . the line cuts y-axis at a point so its co-ordinates are (0,y). Substitute the values of x in the equation. We’ll get P=(2,1) n point Y=(0,3). Distance = sqrt[(1(-3))}2. + (0-2)^2] = sqrt(20) = 2 sqrt(5).
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1. Gurudev said – Mon, 29 Jun 2009 17:51:59 -0000 ( Flag Edit Link )
  
  hi chortle Q 7 is not clear request u to pls explain it furthe.and
  
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2. deepa mittal said – Thu, 02 Jul 2009 04:29:21 -0000 ( Flag Edit Link )
  
  Given y = (x ^ 2) -3
  
  Point P is (2,k) Put x= 2 in given equation, we get y = (2 ^ 2) – 3 y = 1 Hence k = 1 Point P is (2,1) Intersecting point on y axis will have x= 0. So, if x= 0, y = -3
  
  Distance between point P(2,1) and intersecting point(0,-3)
  
  = sqrt(((0-2)^2) + ((-3-1) ^ 2)) = sqrt (4 + 16) = 2 sqrt (5)
  
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Gurudev said – Mon, 29 Jun 2009 17:51:54 -0000 ( Flag Edit Mark / Unmark Best Link )

thanks every body.pls explain other questions also
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deepa mittal said – Thu, 02 Jul 2009 04:50:47 -0000 ( Flag Edit Mark / Unmark Best Link )

Solution 3.

Case 1: If w=1,z=1

Column A: (1 ^ 4) + (1 ^ 3)=2 Column B: (1 ^ 2) + 1=2 Both columns are equal.

Case 2: If w=1, z=2 Column A is greater.

Hence answer is D : It can not be determined.
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