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10 Cards in this Set
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#242
If n is a positive integer, then n(n+1)(n+2) is? a) even only when n is even b) even only when n is odd c) odd whenever n is odd d) divisible by 3 only when n is odd e) divisible by 4 whenever n is even |
e) b/c if n is even then answer is ALWAYS divisible by 4, however, if n is 3 it also works.
(#242) |
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#241
If the integer n has exactly 3 positive divisors, including 1 and n, how many positive divisors does n2 have? |
#241
For any integer to have exactly 3 positive divisors, or factors, it must be the perfect square of a prime number. answer (5) |
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#240
Seed Mixture X is 40% ryegrass and 60% bluegrass by weight; seed mixture Y is 25% rey and 75% other. if a mixture of X and Y contains 30% rye, hat percent of the weight of the mixture is X? a)10% b)33 1/3% c)40% d)50% e)66 2/3% |
40x+25y=30(x+y)
x=1/2y x 1/2y .5 ---- = --------- = ------ = 1/3 x+y 1/2y + y 1.5y |
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#234
Large container is filled with R, Y, G, and B beads, worth 7, 5, 3, 2 each. A number of beads are then removed from container. If the product of the point values of the removed beads is 147,000, how many red beads were removed? 5, 4, 3, 2, or 0? |
make a factor tree for 147,000 and count the # of each of the factors
147,000 210 700 21 10 70 10 3 7 5 2 10 7 5 2 5 2 ---------------------------------- 3, 7, 5, 2, 5, 2, 7, 5, 2 ----------------------------------- |
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#223
Car A is 20 miles behind car B, which is traveling in the same direction along the same route as car A. Car A is traveling at a constant speed of 58 mph and car B is traveling 50 mph. How many hours will it take for car A to overtake and drive 8 miles ahead of car B? 1.5, 2, 2.5, 3, or 3.5 |
dont know how to do this one
28/8 = how is it like that? |
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#196
2:50:100 is the ratio what if you double the first/second ratio? And half first to 3rd? |
2:50 * 2 = 4:50.
2:100 * 1/2 = 1:100 4:50:100, must agree w/new 2nd ratio. 4:50: ? --> 400 1:50:100 But what is y if we have x:100:y 4:50:400 --- 400*100/50 --> 800! |
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#195
What is the shortcut for finding the unique paths between point 0,0 and 2,3 on grid? |
what is short cut other than drawing?
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#209
How many different positive integers are factors of 441? |
441 = 9*49 = 3^2(7^2)
list all possible options 1,3,7,3^2 --> 1,3,7,9 7*3 ---> 21 7*3^2 --> 63 7^2 --> 49 7^2*3 ---> 147 |
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#208
S is a set containing 9 diff. ints. T is a set containing 8 diff. ints. All of which are members of S. Which of the following statements CAN NOT be true? a) the mean of S is equal to the mean of T b) the median of S = median of T c) range of S = range of T d) mean of S > mean of T e) range of S < range of T |
answer is E b/c remember all the number must be distinct so the range of one set must be smaller than the other.
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what does standard deviation mean? example of standard deviation is 0.
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its the spread of numbers.
so if you have 1 1 1 1 1 standard deviation is 1. there is no variation |
