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pls solve maths problems (Discussion)

Gurudev said – Wed, 01 Jul 2009 05:43:18 -0000 ( Edit Link )

1.A person (xxx) wrote a phone number on a note and that was later lost. When he try to recollect, he can remember that the number had 7 digits, the digit ‘1’ appeared in the last three places and digit ‘0’ did not appear at all. What is the probability that the phone number contains at least two prime digits? 2.Given a series -9, 10,-11, 12,-13, 14, -15…........... Col A: The sum of the series till 100 Col B: 45 3.If the median of seven consecutive integers is 2n+2, then find the Arithmetic mean of the sequence? Ans: 2n+2

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fictionfan said – Thu, 02 Jul 2009 09:03:00 -0000 ( Flag Edit Mark / Unmark Best Link )

1. probability = ((4×4) x (9×9)) /(9×9x9×9) ; (4×4) – two places to fill…..4 prime no. available 2,3,5,7 ; (9×9) – rest 2 places can be filled by any 9 digits ; (9×9x9×9) – total combinations possible

2. col A = 46 col B = 45 ; so A>B
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deepa mittal said – Tue, 07 Jul 2009 07:57:23 -0000 ( Flag Edit Mark / Unmark Best Link )

3. Arithmetic mean is the average obtained by adding up all the numbers in the set and dividing by the number of numbers. In this question, since it is a list of seven consecutive integers ,arithmetic mean will be equal to the middle number in the list. Also, the median is equal to the middle number i.e 2n+2. So Arithmetic mean will be 2n+2.
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