Search found 27 matches
- by Admin1
Tue Mar 20, 2018 2:24 pm- Forum: Suggestions and Feedback
- Topic: Delete Account?
- Replies: 100
- Views: 40555
The vertex of the given parabola is at the point (0,4) and it opens up. In order to circle intersects the parabola at only one point we should have the circle with center at the origin and with radius equal to 4. This circle is given by the equation: x^2+y^2=16. We now are interested in finding all ...
- by Admin1
Wed Sep 06, 2017 7:59 pm- Forum: Problem Solving
- Topic: How many points with Integer x and Y co-ordinates lie within
- Replies: 2
- Views: 1488
Since we want to distribute 6 chocolates among 3 children, the exercise is equivalent to find the natural solutions of the equation: x+y+z=6 , where x, y and z represent the 3 children. The solution's sets of this equation are: A={2,2,2}, B={3,2,1}, C={3,3,0}, D={4,1,1}, E={4,2,0} F={5,1,0} and G={6...
- by Admin1
Wed Sep 06, 2017 6:50 pm- Forum: Problem Solving
- Topic: In how many ways can 6 chocolates be distributed among 3 chi
- Replies: 3
- Views: 2255
Answer
For this exercise we need to know this property of the powers: ((a)^n)^m= ((a)^m)^n=(a)^n*m . Also, there is a formula that can help us to solve this exercise, which is: a^2-b^2=(a-b)*(a+b) . We have this expression: 4^17-2^26 . Now we can write: 4=2^2 and using the red formula at the beginning we w...
- by Admin1
Wed Sep 06, 2017 4:12 pm- Forum: Problem Solving
- Topic: Please help with this one
- Replies: 7
- Views: 4099
Time rate and distance
Here's a more technical math solution as well : Based on the given values, let the coordinates at Centerville Station be 0 and that at Dale City Station be 90 miles, and Train A: x 0A = 0 t 0A = 3 hr v 0A = v A = +30 miles/hour Train B: x 0B = 90 miles t 0B = (3 + 1/3) hr = (10 / 3) hr v 0B = v B =...
- by Admin1
Tue Sep 05, 2017 11:07 pm- Forum: Problem Solving
- Topic: Time rate and distance
- Replies: 8
- Views: 5812
Time rate and distance
The question had me stumped because i forgot which formula i had to use, either d*r/t or r*d/t. The question is as follows: Train A left Centerville Station, heading toward Dale City Station at 3:00pm. Train B left Dale City Station heading toward Centerville Station at 3:20pm. on the same day. The...
- by Admin1
Tue Sep 05, 2017 10:32 pm- Forum: Problem Solving
- Topic: Time rate and distance
- Replies: 8
- Views: 5812
multiples of 7
A streamlined solution:
84 / 7 = 12
140 / 7 = 20
So, it would be seven multiple of 12, 13, 14, 15, 16, 17, 18, 19 and 20.
Thus the sum of the multiples of 7 from 84 to 140, inclusive, is:
7(12 + 13 + 14 + 15 + 16 + 17 + 18 + 19 + 20) = 7 (144) = 1008.
Answer: C
- by Admin1
Tue Sep 05, 2017 9:58 pm- Forum: Problem Solving
- Topic: multiples of 7
- Replies: 9
- Views: 11201
What is the sum of the multiples of 7 from 84 to 140, inclusive? A)896 B)963 c)1008 D)1792 E)2016 OA C How to approach this kind of question? Solution: Sum of the multiples of 7 from 84 to 140, inclusive, 84 + 91 + 98 + 105 + ... +140 This above series represents an arithmetic series with a common ...
- by Admin1
Tue Sep 05, 2017 9:44 pm- Forum: Problem Solving
- Topic: multiples of 7
- Replies: 9
- Views: 11201
A positive number x is multiplied by 2, and this product is then divided by 3. If the positive square root of the result of these two operations equals x, what is the value of x ? (A) 9/4 (B) 3/2 (C) 4/3 (D) 2/3 (E) 1/2 OA: D Please share the solution for this problem. Solution: A positive number x...
- by Admin1
Tue Sep 05, 2017 9:17 pm- Forum: Problem Solving
- Topic: OG2016 PS A positive number x
- Replies: 8
- Views: 2536
- by Admin1
Tue Sep 05, 2017 4:37 pm- Forum: Problem Solving
- Topic: OG2016 PS A positive number x
- Replies: 8
- Views: 2536
If a 30%-solution of alcohol was mixed with
If a 30%-solution of alcohol was mixed with a 50%-solution of alcohol to obtain 10 liters of a 45%-solution of alcohol, how much of the 30%-solution was used? A. 2.0 liters B. 2.5 liters C. 2.7 liters D. 3.0 liters E. 3.2 liters Solution: Let 30%-solution of alcohol be 'x' litres. Then 50%-solution ...
- by Admin1
Tue Sep 05, 2017 1:04 pm- Forum: Problem Solving
- Topic: If a 30%-solution of alcohol was mixed with
- Replies: 6
- Views: 3147
OG2016 PS If x = -1,
If x = -1, then (x^4 - x^3 + x^2)/(x - 1) =? ((-1)^4 - (-1)^3 + (-1)^2)/((-1) - 1) We know that any negative number raised to an odd power results into a negative number and any negative number raised to an even power results in to a positive number. In other words, x^n is a negative number if n is ...
- by Admin1
Tue Sep 05, 2017 12:39 pm- Forum: Problem Solving
- Topic: OG2016 PS If x = -1,
- Replies: 9
- Views: 3071
Solution:
Recall, that,
(-1)^p = -1 if p is odd
= +1 if p is even.
So, substituting the given value of x into the expression, we have
((+1) - (-1) + (+1)) / ((-1) - 1) = 3/(-2) = - 3/2.
Answer: A
- by Admin1
Tue Sep 05, 2017 6:46 am- Forum: Problem Solving
- Topic: OG2016 PS If x = -1,
- Replies: 9
- Views: 3071
Solution : 36^2 = (6^2)^2 = 6^4 = (2 x 3)^4 = (2^4)(3^4) So, if n is a factor of 36^2, then n = (2^ a )(3^ b ), where 0 <= a <= 4, 0 <= b <= 4. For a , there are five choices: 0, 1, 2, 3, 4. Similarly there are five choices for b . For each choice of a , b , there is a different factor for 36^2. Th...
- by Admin1
Tue Sep 05, 2017 5:44 am- Forum: Problem Solving
- Topic: How many factors of 36^2?
- Replies: 8
- Views: 3431
Solution : Firstly, it is important to know the meaning of the expression, [x], which is the least integer greater than or equal to x. For example, [2.3] = 3. Now, in order to know how many half-miles there are in r miles, we have r / (1/2) = 2 r. But, a fraction of a half-mile will still be counte...
- by Admin1
Mon Sep 04, 2017 6:18 pm- Forum: Problem Solving
- Topic: For each trip, a taxi company charges a fixed fee of $2.00
- Replies: 11
- Views: 7269