<p>Thanks man</p>
<p>If the unit digit of 3power36 is N and the unit digit of 4power1525 is m find m+n.
Can any one do this</p>
<p>^ What are the chances that the power of 3^x are an enless loop of 3,9,7,1 in a certain order? And that the power of 4 alternate between 4 and 6? Run a couple of series and analyze the patterns. </p>
<p>3^1 3
3^2 9
3^3 7
3^4 1</p>
<p>3^5
3^6
3^7
3^8
rinse and repeat until you see the pattern</p>
<p>4^1
4^2</p>
<p>4^3
4^4</p>
<p>following on from xiggi’s post…finding N: since 36 is a multiple of 4, the units digit of 3^36 is 1 (same as 3^4), N=1
finding M: since 1525 is odd, the units digit of 4^1525 is 4 (same as 4^1), M= 4
N+M = 5</p>
<p>1over2,1over6,1over12,…
Find the sum of the 50th term
Can anyone answer this ??</p>
<p>Can u explain how did u get it ??</p>
<p>@Abdelrahmanayman this is a fairly classic problem on telescoping series (I’ve seen similar problems in many places). The trick is to note that 1/2 = 1 - 1/2, 1/6 = 1/2 - 1/3, 1/12 = 1/3 - 1/4, etc. so 1/2 + 1/6 + … + 1/(50*51) = 1 - 1/51 = 50/51.</p>
<p>Sorry the question is missing.
1/2,1/6,1/12…
find the sum of the first 50th term</p>
<p>Fwiw, when posting problems, it is very important to reproduce them correctly. It is important because problems might have been transposed incorrectly over time, and end up being misleading. The last problem is still incorrectly posted. What you need to find is the sum of a number of terms — and not the xth one. Details are important. </p>
<p>Fwiw, the answer posted by Jor is simple and elegant (and of course correct.) Recognizing patterns on the SAT is both important and rather easy as the patterns tend to be very simple. </p>
<p>PS This is not a criticism of MIT’s solution by any means!
PPS Worth reading > <a href=“http://qa.■■■■■■■■■■■■■/post/69000416580/help-1-1-2-1-2-3-1-3-4-the-first”>http://qa.■■■■■■■■■■■■■/post/69000416580/help-1-1-2-1-2-3-1-3-4-the-first</a></p>
<p>Hey xiggi, part of the link got hidden. Could you provide the missing info please?</p>
<p>The hidden part is “pwnthesat. com”</p>
<p>Hi! I took the PSAT back in October. Can someone please estimate my score if… </p>
<p>CR Part 1: Skipped 8. 
Maybe 3-4 wrong.
Math Part 1: Skipped 2 1-2 Wrong
CR Part 2: Skipped 3 3-4 wrong?
Math Part 2: All correct maybe 1-2 wrong on fill-in the rest were all right.
Writing: 2-3 wrong</p>
<p>for question 1. its C , first there is a number that can be divided b “15 and 25” which is 5 , then Add 15+25=40 , I tried choice C (n+75) , (5+75=80) then divide 80/40 which equals a whole number which is 2 , the rest of the choices will equal to fractions and “n” is a real whole number.</p>
- Shawn creates a meal by mixing the pastas, sauces, and toppings in his kitchen. Each meal he creates consists of one type of pasta, one sauce, and one type of topping. If Shawn can make exactly 30 different meals, which of the following could NOT be the number of sauces that Shawn has? (A) 1 (B) 2 (C) 3 D) 4 (E) 5
D) 4. The # of different meals he can make is equal to the product of number of types of pasta, number of sauces, and number of toppings, so basically the product of 3 positive integers is 30. Every choice is a factor of 30 except 4.
Hey! Could anybody help me with these problems from the CB 2ed.:
-(p.861 #15) A store charges$28 for a certain type of sweater. This price is 40 percent more than the amount it costs the store to buy one of these sweaters. At an end-of-season sale, store employees can purchase any remaining sweaters at 30 percent off the store"s cost. How much would it cost an employee to purchase a sweater of this type at the sale?
(A) $8.40
(B) $14.00
© $19.60
(D) $20.00
(E) $25.20
-(p.702 #11) The sequence above may be changed in either of two ways. Either two adjacent letters may be interchanged or the entire sequence may be reversed. What is the least number of such changes needed to put the letters into alphabetical order from left to right?
(A) 2
(B) 3
© 4
(D) 5
(E) 6
-(p.642 #17) In the xy-plane, line l passes through the origin and is perpendicular to the line 4x+y=k, where k is a constant. If the two lines intersect at the point (t,t+1), what is the value of t?
(A) -4/3
(B) -5/4
© 3/4
(D) 5/4
(E) 4/3
-(p.417 #13) In the 30-day month of April, for every three days it rained, there were two days it did not rain. The number of days in April on which it rained was how much greater than the number of days on which it did not rain?
Answers: (B) $14.00
(B) 3
(A) -4/3
6
Thank you!
First question:
Let x be the amount it costs the store to buy a sweater. We are given that 28 is 40 percent more than x. As an equation this is 28 = 1.4x. So we have that the store’s cost is x = 28/1.4 = 20. We must now take 30 percent off of 20. Taking 30 percent off of 20 is the same as taking 70 percent of 20. So the answer is .7(20) = 14, choice (B).
Remarks: (1) We change a percent to a decimal by moving the decimal point to the left two places. The number 70 has a “hidden” decimal point after the 0. So 70 percent as a decimal is .70 = .7.
(2) We can also take 30 percent off of 20 by taking 30 percent of 20 and then subtracting this from 20.
So 30 percent of 20 is .3(20) = 6. Thus, 30 percent off of 20 is 20 – 6 = 14.
Second question:
Let’s attempt to put the letters in alphabetical order in as few steps as possible:
Z W Y X X Y W Z X W Y Z W X Y Z
We did it in three steps. So it seems like the answer is choice (B).
Notes: For the first step we reversed the entire sequence. For the second and third steps we interchanged two adjacent letters.
It should be clear that if we start with a reversal of the whole sequence, we need two more steps to put the letters in alphabetical order. Getting the W to the other side of the X takes two steps, and reversing the sequence another step. So if we start by moving the W it will still take three steps. If instead we begin by trying to get X to the other side of W, then this will take two steps. We still need to get Y to the other side of the W, and then the Z will still be in the wrong position. So this will take more steps. Similarly if we start by moving Y or Z.
Third question:
Let’s put the given line into slope-intercept form by subtracting 4x from each side of the equation. We get y = -4x + k, and we see that the slope of this line is -4. Since line l is perpendicular to this line, line l has a slope of 1/4. Since line l passes through the origin (the point (0,0)), it follows that the equation of line l is y = 1/4x. Since the point (t,t + 1) is on line l, we have t + 1 = 1/4t. We need to solve this last equation for t.
t + 1 = 1/4t
4t + 4 = t
3t + 4 = 0
3t = -4
t = (-4)/3
Therefore the answer is choice (A).
Last one:
It rained on (3/5)(30) = 18 of the days in April. Therefore it didn’t rain on 30 – 18 = 12 of the days of April. Finally, 18 – 12 = 6.
Formal Algebra: 3x + 2x = 30, so that 5x = 30 or x = 6. Then 3x = 3(6) = 18 and 2x = 2(6) = 12. Finally 3x – 2x = x = 6.