math problem of the day

### Author Topic: math problem of the day  (Read 1043 times)

#### jas_fluidm

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##### math problem of the day
« on: July 18, 2013, 02:31:08 PM »
L= {-6, -5, -4, -3, -2}
P = {-2, -1, 0, 1, 2, 3}

If an integer is to be randomly selected from set L above and an integer is to be randomly selected from set P above, what is the probability that the product of the two integers will be negative?

A. 0
B. 1/3
C. 2/5
D. 1/2
E. 3/5

#### jas_fluidm

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##### Re: math problem of the day
« Reply #1 on: July 18, 2013, 02:33:08 PM »
no. of possible values to be negative/all possible values from the sets
=5*3/5*6
=1/2

#### jas_fluidm

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##### Re: math problem of the day
« Reply #2 on: July 18, 2013, 02:34:08 PM »
in order to get negative integer either m should be negative and n positive
probability of L is negative =5/5=1
probability of P is positive 3/6=1/2
probability of m negative and m positive is 1*1/2=1/2

#### jas_fluidm

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##### Re: math problem of the day(another)
« Reply #3 on: July 18, 2013, 02:36:15 PM »
The sum of the even numbers between 1 and k is 79*80, where k is an odd number, then k=?

#### jas_fluidm

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##### Re: math problem of the day
« Reply #4 on: July 18, 2013, 02:46:04 PM »

#### jas_fluidm

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##### Re: math problem of the day
« Reply #5 on: July 18, 2013, 02:46:46 PM »
A certain right circular cylinder has a radius of 5 inches. There is a kind of liquid filled in this cylinder to the height of 9 inches. If this liquid is poured completely into a second right cylinder, then the liquid will fill the second cylinder to the height of 4 inches. What is the radius of the second cylinder, in inches?

#### jas_fluidm

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##### Re: math problem of the day
« Reply #6 on: July 18, 2013, 02:52:59 PM »

Volume of 1st cylinder=2*pi*5^2*9
Volume of 2nd cylinder=2*pi*r^2*4
so, 5^2*9=r^2*4
=> r=Sq rt(25*9/4)=7.5

#### mohin

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##### Re: math problem of the day
« Reply #7 on: July 21, 2013, 04:24:53 PM »
The sum of the even numbers between 1 and k is 79*80, where k is an odd number, then k=?

Md. Mohin chowdhury

#### Khandoker Samaher Salem

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##### Re: math problem of the day
« Reply #8 on: July 28, 2013, 11:36:55 AM »
Nice post.
Khandoker Samaher Salem
Lecturer (ACCT)
Dept. of Textile Engineering, FE
samaher@daffodilvarsity.edu.bd