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Alternatively:
Imagine a 3-digit integer: PQR
P has 4 values, Q has 4 values, R has 4 values
There are 4^3 = 48 combinations
If we dismiss P=Q=R, that removes 4 combinations
If we dismiss P=Q, Q=R and P=R, that removes 3 x 4 = 12 combinations
So, 48 - 4 - 12 = 32 combinations
- by Mathsbuddy
Thu Nov 27, 2014 8:17 am- Forum: Problem Solving
- Topic: manhattan
- Replies: 10
- Views: 3480
So, 12(x -2) + 12x = 5x(x-2) Rearrange to make a quadratic: 5x^2 - 34x + 24 = 0 (5x-4)(x-6) = 0 x = 4 or 6 As X takes 2 days longer than Y, then x = 6, y = 4 to make w widgets Therefore, 2w widgets take X 12 days to make. The highlighted step should be x = 4/5 or 6 Well spotted... oops! Thanks for ...
- by Mathsbuddy
Thu Nov 27, 2014 8:06 am- Forum: Problem Solving
- Topic: Difficulty Level
- Replies: 12
- Views: 3355
Using the Equation of a Circle is certainly the right way to go. However for speed, you could try this: With a range from y = -1 to y = 7, it is easy to recognise that the radius is 4. As the centre of the circle is not lying on the x-axis, it means that it must intersect the x-axis at a value less...
- by Mathsbuddy
Thu Nov 27, 2014 8:03 am- Forum: Problem Solving
- Topic: The center of circle Q is on the y-axis, and the circle pass
- Replies: 7
- Views: 5132
I like your method... very quick, but 20 and 44 are both less than 48 Note that as we need an integer bigger than 48, we could save more time by only looking at values that are >=48 Divided by 6 has remainder 2 = 50, 56, 62, 68 , 74, etc... Divided by 8 has remainder 4 = 52, 60, 68 , e Our lowest c...
- by Mathsbuddy
Thu Nov 27, 2014 7:51 am- Forum: Problem Solving
- Topic: REMAINDER PROBLEM GOOD ONE...
- Replies: 13
- Views: 4312
Rate = w/time: w/x = w/(y + 2) or w/y = w/(x - 2) where x and y are measures of time Together: w/x + w/(x - 2) = (5w/4)/3 So, 12(x -2) + 12x = 5x(x-2) Rearrange to make a quadratic: 5x^2 - 34x + 24 = 0 (5x-4)(x-6) = 0 x = 4 or 6 As X takes 2 days longer than Y, then x = 6, y = 4 to make w widgets Th...
- by Mathsbuddy
Thu Nov 27, 2014 4:08 am- Forum: Problem Solving
- Topic: Difficulty Level
- Replies: 12
- Views: 3355
Using the Equation of a Circle is certainly the right way to go. However for speed, you could try this: With a range from y = -1 to y = 7, it is easy to recognise that the radius is 4. As the centre of the circle is not lying on the x-axis, it means that it must intersect the x-axis at a value less ...
- by Mathsbuddy
Thu Nov 27, 2014 2:05 am- Forum: Problem Solving
- Topic: The center of circle Q is on the y-axis, and the circle pass
- Replies: 7
- Views: 5132
HI Math Experts, This is not exactly any question from any Test prep companies. Rather it's just a basic question to get some clarification on my doubts, so that I can have better understanding of the actual problem. Here's the question - In how many ways can a person post 5 letters in 4 letter box...
- by Mathsbuddy
Wed Nov 26, 2014 7:35 am- Forum: Problem Solving
- Topic: Seeking conceptual clarity on Permutation
- Replies: 8
- Views: 1915
I like your method... very quick, but 20 and 44 are both less than 48 Note that as we need an integer bigger than 48, we could save more time by only looking at values that are >=48 Divided by 6 has remainder 2 = 50, 56, 62, 68 , 74, etc... Divided by 8 has remainder 4 = 52, 60, 68 , e Our lowest co...
- by Mathsbuddy
Wed Nov 26, 2014 7:29 am- Forum: Problem Solving
- Topic: REMAINDER PROBLEM GOOD ONE...
- Replies: 13
- Views: 4312
Note that Answer 5 should be: >=20 (not <=20) An integer when divided by 6 has remainder 2 and when divided by 8 gives remainder 4. What is the remainder when the integer is divided by 48? 1. 0 2. between 1 and 6 3. between 7 and 12 4. between 13 and 19 5. <= 20 [spoiler]OA: E[/spoiler]
- by Mathsbuddy
Wed Nov 26, 2014 7:12 am- Forum: Problem Solving
- Topic: REMAINDER PROBLEM GOOD ONE...
- Replies: 13
- Views: 4312
Nice Graph!!! But GMAT doesn't allow us leisure of time that we can be that creative. Relative Distance to be travelled = 120 + 45 = 165 Miles Relative Speed (Opp.Dir) = 49 + 61 = 110 Miles/Hr Time = Distance / Speed = 165 / 110 = 1.5 Hour from the state of Journey i.e. they meet at 3:30 PM Answer:...
- by Mathsbuddy
Wed Nov 26, 2014 7:09 am- Forum: Problem Solving
- Topic: Cars P & Q are approaching each other on the same highwa
- Replies: 4
- Views: 1890
As divisors and remainders are all even numbers, we can simplify the problem by halving all values: I = 3x + 1 = 4y + 2 = 24z + 0.5R Test possible values of x: For even values of x, y is unachievable If x = 1, I = 4, y is unachievable If x = 3, I = 10, y = 2, z is unachievable If x = 5, I = 16, y is...
- by Mathsbuddy
Mon Nov 24, 2014 7:02 am- Forum: Problem Solving
- Topic: REMAINDER PROBLEM GOOD ONE...
- Replies: 13
- Views: 4312
A sketch can help (see graph).
Then using y = mx + c for each car:
Distance between P and Q = pt – (qt + 120) = 45
So, t = (45 + 120)/(p-q) = 165/(49 - -61) = 165/110 = 1.5
Therefore clock time = 2pm + 1.5h = 3.30pm
- by Mathsbuddy
Mon Nov 24, 2014 6:32 am- Forum: Problem Solving
- Topic: Cars P & Q are approaching each other on the same highwa
- Replies: 4
- Views: 1890
How can I find out how many times number 3 appears in 1 to 1000 ?
Assuming "number" means digit,
in binary it doesn't appear at all!
- by Mathsbuddy
Fri Nov 21, 2014 9:38 am- Forum: Problem Solving
- Topic: How many times 3 appear in 1 to 1000 ?
- Replies: 17
- Views: 110326
Statement 2 is clearly insufficient as it is higher order to the objective equation. Let me explain: (x-2)(y-3)=6 has highest order xy (if x = y, then it would be quadratic) (x-8)(y²+5) =0 has highest order xy² (if x = y, then it would be cubic) As such, the possible number of solutions to Stateme...
- by Mathsbuddy
Fri Nov 21, 2014 9:35 am- Forum: Data Sufficiency
- Topic: if x and y are positve...
- Replies: 3
- Views: 1886
Alternative method, perhaps?
By comparing sides of similar triangles (ratio), area and other geometric facts, can anyone find a way of using the attached graph to solve this problem? I've labelled all intersections to help a writer describe their solution.
- by Mathsbuddy
Fri Nov 21, 2014 9:21 am- Forum: Problem Solving
- Topic: Two Cyclists
- Replies: 3
- Views: 5869