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5 Math Questions: Please Help [#permalink]
27 Jan 2008, 12:16

1

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Hello, can somebody please help me solve the following 5 questions. Thank you very much.

1. What is the greatest prime factor of 4^17 – 2^28? The correct answer is 7.

2. If K is a positive integer, is K the square of an integer? i) K is divisible by 4 ii) K is divisible exactly by 4 different prime numbers. The correct answer is e, statement i and ii together are NOT sufficient.

3. The symbol * represents one of four arithmetic options, plus, minus, divide, or multiply. Is (5*6)*2 = 5*(6*2)? i) 5*6 = 6*6 ii) 2*0 = 2 The correct answer is a, statement i alone is sufficient.

4. Five pieces of wood have an average length of 124 cm and a median length of 140cm. what is the maximum possible length of the shortest piece of wood? The correct answer is 100cm

5. Machine A produces pencils at a constant rate of 9000/hour. Machine B produces pencils at a constant rate of 7000/hour. If the two machines together must produce 100,000 pencils, and if each machine can operate for at most 8 hours, what is the least amount of time that machine B must operate. The correct answer is 4 hours.

Re: 5 Math Questions: Please Help [#permalink]
27 Jan 2008, 12:28

Expert's post

leizermike wrote:

2. If K is a positive integer, is K the square of an integer? i) K is divisible by 4 ii) K is divisible exactly by 4 different prime numbers. The correct answer is e, statement i and ii together are NOT sufficient.

\(K=2^2*3^2*5^2*7\) and \(K=2^2*3^2*5^2*7^2\) are satisfy both conditions but only one is the square of an integer. E _________________

Re: 5 Math Questions: Please Help [#permalink]
27 Jan 2008, 12:34

Expert's post

leizermike wrote:

3. The symbol * represents one of four arithmetic options, plus, minus, divide, or multiply. Is (5*6)*2 = 5*(6*2)? i) 5*6 = 6*6 ii) 2*0 = 2 The correct answer is a, statement i alone is sufficient.

I think It have to be 5*6=6*5.

(5*6)*2 = 5*(6*2) is true for "+", "*" and is false for "-", "/"

1. 5*6=6*5 is true for "+", "*". sufficient.

2. 2*0=2 is true for "+", "-".insufficient. _________________

Re: 5 Math Questions: Please Help [#permalink]
27 Jan 2008, 12:36

Expert's post

leizermike wrote:

4. Five pieces of wood have an average length of 124 cm and a median length of 140cm. what is the maximum possible length of the shortest piece of wood? The correct answer is 100cm

Re: 5 Math Questions: Please Help [#permalink]
27 Jan 2008, 12:40

Expert's post

leizermike wrote:

5. Machine A produces pencils at a constant rate of 9000/hour. Machine B produces pencils at a constant rate of 7000/hour. If the two machines together must produce 100,000 pencils, and if each machine can operate for at most 8 hours, what is the least amount of time that machine B must operate. The correct answer is 4 hours.

Re: 5 Math Questions: Please Help [#permalink]
27 Feb 2008, 22:15

walker wrote:

leizermike wrote:

5. Machine A produces pencils at a constant rate of 9000/hour. Machine B produces pencils at a constant rate of 7000/hour. If the two machines together must produce 100,000 pencils, and if each machine can operate for at most 8 hours, what is the least amount of time that machine B must operate. The correct answer is 4 hours.

Re: 5 Math Questions: Please Help [#permalink]
28 Feb 2008, 01:33

walker wrote:

leizermike wrote:

3. The symbol * represents one of four arithmetic options, plus, minus, divide, or multiply. Is (5*6)*2 = 5*(6*2)? i) 5*6 = 6*6 ii) 2*0 = 2 The correct answer is a, statement i alone is sufficient.

I think It have to be 5*6=6*5.

(5*6)*2 = 5*(6*2) is true for "+", "*" and is false for "-", "/"

1. 5*6=6*5 is true for "+", "*". sufficient. 2. 2*0=2 is true for "+", "-".insufficient.

walker, 5*6=6*5 is true for "+", "x" but how is that suff?

if * is "x", suff. if * is "+", insuff. _________________

1. 5*6=6*5: plus: (5+6) = (6+5) true multiply: (5x6) = (6x5) true minus: (5-6) = (6-5) false divide: (5/6) = (6/5) false Therefore, condition 1 points that * could be + or x. For both operations (5*6)*2 = 5*(6*2) is true. So, information is sufficient to answer the question.

Therefore, condition 2 points that * could be + or -. For each operations (5*6)*2 = 5*(6*2) can be true (+) or false (-). So, information is not sufficient to answer the question. _________________