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If an integer is to be randomly selected from set M above [#permalink]
12 Jan 2008, 04:29

00:00

A

B

C

D

E

Difficulty:

25% (low)

Question Stats:

64% (01:50) correct
35% (00:54) wrong based on 178 sessions

M = {-6, -5, -4, -3, -2} T = {-2, -1, 0, 1, 2, 3}

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

If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T 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

I think D is correct in order to get negative integer either m should be negative and n positive probability of m is negative =5/5=1 probability of n is positive 3/6=1/2 probability of m negative and m positive is 1*1/2=1/2

If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T 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

P= No of ways the product of two integers is negative/All possible values = 5*3/5*6 =1/2
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If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T 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

Soln: Total number of possible ways of choosing two integers is = 5 * 6 = 30 ways Now for the product of two integers to be chosen to be negative = they should be of opposite sign. Since set M has all negative numbers, thus we move to set T which has 3 positive numbers. Thus total number of possible ways in which product will be negative is = 5 * 3 = 15

Probability that the product of the two integers will be negative = 15/30 = 1/2 Ans is D

If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T 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

Negative prod pairs = 5 x 3 = 15 total pairs possible = 5c1 x 6c1 = 5 x 6 = 30

Probability = 15 / 30 = 1/2
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If product has to be negative then m is -ve and n is +ve or m is +ve and n is -ve. But all elements of m are -ve hence we need n to be +ve. 0 has to be excluded as any number multiplied by 0 is 0 and it is neither +ve nor -ve.

Re: M = {-6, -5, -4, -3, -2} T = {-2, -1, 0, 1, 2, 3} If an [#permalink]
30 Mar 2012, 23:25

Hello,

I got a doubt. Any no. mulitplied by 0 is 0 and 0 is neither +ve nor -ve. Going by this prop of 0, y shld we consider 0 as one of the nos. cause any no +ve or -ve multiplied by 0 is neither positive nor negative ?

Re: M = {-6, -5, -4, -3, -2} T = {-2, -1, 0, 1, 2, 3} If an [#permalink]
31 Mar 2012, 00:34

2

This post received KUDOS

Expert's post

priyalr wrote:

Hello,

I got a doubt. Any no. mulitplied by 0 is 0 and 0 is neither +ve nor -ve. Going by this prop of 0, y shld we consider 0 as one of the nos. cause any no +ve or -ve multiplied by 0 is neither positive nor negative ?

Thnx.

It's not clear what you mean by "why should we consider 0 as one of the numbers"... Anyway:

M = {-6, -5, -4, -3, -2} T = {-2, -1, 0, 1, 2, 3} If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T 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

In order the product of two multiples to be negative they must have different signs. Since Set M consists of only negative numbers then in order mt to be negative we should select positive number from set T, the probability of that event is 3/6=1/2, (since out of 6 number in the set 3 are positive).

Re: M = {-6, -5, -4, -3, -2} T = {-2, -1, 0, 1, 2, 3} If an [#permalink]
05 Oct 2012, 21:26

Bunuel wrote:

priyalr wrote:

Hello,

I got a doubt. Any no. mulitplied by 0 is 0 and 0 is neither +ve nor -ve. Going by this prop of 0, y shld we consider 0 as one of the nos. cause any no +ve or -ve multiplied by 0 is neither positive nor negative ?

Thnx.

It's not clear what you mean by "why should we consider 0 as one of the numbers"... Anyway:

M = {-6, -5, -4, -3, -2} T = {-2, -1, 0, 1, 2, 3} If an integer is to be randomly selected from set M above and an integer is to be randomly selected from set T 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

In order the product of two multiples to be negative they must have different signs. Since Set M consists of only negative numbers then in order mt to be negative we should select positive number from set T, the probability of that event is 3/6=1/2, (since out of 6 number in the set 3 are positive).

Answer: D.

Hope it's clear.

Why us 0 not considered as the product of any number will give non negetive

gmatclubot

Re: M = {-6, -5, -4, -3, -2} T = {-2, -1, 0, 1, 2, 3} If an
[#permalink]
05 Oct 2012, 21:26