Jen1984

Hi, I am a little ashamed about the following question but it would be great if someone could help me: (1/2)^10 + (1/2)^10 = (1/2)^9 What is the step to pass from one to the other? Thanks

Hey guys, this is a DS problem which means that you don't have to solve anything! You just need to know that there is a way to solve it...

Yes but what if I use a = 8 b = 2 Then, (a-b) = 6 and (a/b) = 4 In this case, the answer would be B. From what the question tells us why can I not solve the problem like this?

Supersuj, Is this general rule? In what other cases can it be applied? Thanks!

sorry but... could you just explain to me ignorant how you pass from 5^21 * 2^22 to 2*10^21? Thanks!

yes but 9 and 6 are equal to m and not to m...???

mmesarina, On both problems you have to find integers for x and y. Let's look at the pencil problem: 21x * 23y = 130 If you try with integers values for x and y you will see that the only combination that works is x = 4 and y = 2 Now, let's look at the donut problem: 0.40x + 0.30y = 6 If you try different integers for x and y you will see that more than one combination works: x = 3 ; y = 16 x = 6 ; y = 12 .... Thus, the difference between the two problems (and that's what makes one solvable and the other not) is that in one case you can find a unique solution and in the other not...

For all positive integers m, m=3m when m is odd and m=(1/2)m when m is even. Which of the following is equivalent to 9 * 6 ? 81 54 36 27 18

If (5^21) * (4^11) = 2 * (10^n) what is the value of n?

If m, r, x and y are positive, is the ratio of m to r equal to the ratio of x to y? (1) The ratio of m to y is equal to the ratio of x to r. (2) The ratio of m+x to r+y is equal to the ratio of x to y.

In a rectangular coordinate system, does line k intersect quadrant II? (1) The slope of k is -1/6 (2) The y-intercept of k is -6

If x and y are positive integers, what is the value of xy? (1) The greatest common factor of x and y is 10. (2) The least common multiple of x and y is 180.

Thank you Genius!

It's correct. How do you know that it will have 100 0's? Thanks!

What is the least number of digits (including repetitions) needed to express 10^100 in decimal notation? (A) 4 (B) 100 © 101 (D) 1,000 (E) 1,001

You know that a can is 12-ounce if either concentrate or water. When you want to make an orange juice you actually need 4 cans (one of concentrate and four of water). So, when you use one can of concentrate you "produce" 48-ounces of orange juice (= 4*12). The question is: how many cans of concentrate you will need for 200*6 = 1'200 ounces of orange juice. You know that for 48 ounces you need one can. So, for 1'200 ounces you need 25 cans hence A.

Fox jeans regularly sell for $15 a pair and Pony jeans regularly sell for $18 a pair. During a sale these regular unit prices are discounted at different rates so that a total of $9 is saved by purchasing 5 pairs of jeans: 3 pairs of Fox jeans and 2 pairs of Pony jeans. If the sum of the two discounts rates is 22 percent, what is the discount rate on Pony jeans? (A) 9% (B) 10% © 11% (D) 12% (A) 22% (E) 15% The problem seems to be easy but I don't know why I cannot come to the right answer... Somewhere I must be doing something wrong...

Thank you very much kool_sunny! Great explanation!

2. A box contains 70 mobile phones 20 of which are defective. If 8 phones are randomly selected from the box, what is the chance that at least 7 of them will be working? The probability that at least 7 phones will work: P(7) + P(8). P(7) = (50/70) * (49/69) * (48/68) * (47/67) * (46/66) * (45/65) * (44/64) = 0.083 P(8) = (50/70) * (49/69) * (48/68) * (47/67) * (46/66) * (45/65) * (44/64) * (43/63) = 0.0569 P(7) + P(8) = 0.083 + 0.0569 = 0.14

Thank you! But how come you solve the problem like this?

What is the units digit of (13^4) * (17^2) * (29^3)? (A) 9 (B) 7 © 5 (D) 3 (E) 1 What is the easiest way to proceed here?

IMO it's two ways: + - + - + - + - + - - + - + - + - + - +

You musn't forget that the sum of the numbers in list S is equal to the sum of the numbers in list T. So the only way that the AM of S is smaller than the AM of T is that S has more integers in its list.

1) the proba that at least one call will arrive = 1-Proba that 0 call will arrive. 2) the proba taht at least 7 of the working phones will come out = P(7) + P(8) 3) you know that the variance = (SD)^2 If you consider a normal distribution, tis mean and its SD you can find the probability of one value being in a given interval.

My answer would be 560. (but am really bad in these things...). The first person is 10! / 9! The two other persons are 8! / 6! The product of the two = 560. Could someone explain?