SAT Math Problems Thread

<ol>
<li>When 53 is divided by a positive integers n, the remainder is 3. How many values of n are possible? Can someone explain how to solve this problem . :D</li>
</ol>

<p>Here is a big hint: 53 - 3 = 50 must be divisible by n, and n must be greater 2.</p>

<p>@DrSteve‌ So what do I do next? Sorry, I suck at remainders :(</p>

<p>@iStudy there are two possible values of n which are 25 and 50.</p>

<p>When an integer, say m, is divided by another integer, say n, leaving a remainder of k, the integer m = n or the multiple of n + k.</p>

<p>In this case m = 53 and k = 3 :
53 = n+3
53 - 3 = n
n = 50</p>

<p>53/50 = 1 with a remainder of 3</p>

<p>53 = 2n + 3
53 - 3 = 2n
50 = 2n
n = 50/2
n = 25 </p>

<p>53/25 = 2 with a remainder of 3</p>

<p>@tribecca3‌ But the answer keys says there are 4 possible values. 50, 25, 10 and 5. </p>

<p>@‌ istudy</p>

<p>We are basically looking for divisors of 50 because any divisor of 50 except 1 and 2 has a remainder of 3 when divided into 53. Counting divisors we have 5, 10, 25, 50, so the answer is 4. </p>

<p>@kkpanu9‌ @Jor26029‌ Thanks guys for explaining :)</p>

<p>I was actually rushing when I gave that answer. You guys are right; there are more than two possible values, four precisely.</p>

<p>A teacher has 36 students in a classroom. She sets up the classroom with 8 rows that have 5 seats in each row. What is the probability of a student getting chosen to sit in the 8th row?</p>

<p>I was thinking 1/36 since there is only 1 seat in row 8, but it wasn’t on option. I only remember four options:
2/9
1/5
1/10
1/8</p>

<p>Probability = desired outcomes/total number of outcomes</p>

<p>Since there are the same number of seats in each row:</p>

<p>desired number of outcomes: 1 row </p>

<p>Total umber of outcomes: 8 rows</p>

<p>==> 1/8 </p>

<p>(You’re wrong because you’re assuming the teacher is seating people sequentially (i.e- form seat 1, then 2 then 3 …till 36),. while in actuality the teacher is seating the people randomly.)
Here’s my solution:
5 seats in row 8, out of 40 total seats. The possibility that a person is chosen for row 8 is 5/40 - 1/8. They’ve only given that there are 36 people to tell you that there aren’t 40 people, who will populate the entire classroom, thus making the probability 1. </p>

<p>My only concern is that the question is ambiguous as to whether the person chosen by the teacher is the first person. For example, lets say 1 person is asked to sit on the first seat. Then the possibility of getting put on the 8th row becomes 5/39. Similarly, by the time 35 students have sat down, assuming NONE of them is in row 8, the one person left will HAVE to sit on row 8, thus making the probability a solid 1.</p>

<p>@thezealot‌ -
x=2 is a straight line parallel to the y axis. Thus any line with equation of y=c, c is a constant, will be parallel to the x axis, and thus perpendicular to x=a , a is a constant. This cannot be done exactly because the slope of x=2 is not defined as its parallel to the x axis, and m=tanθ , and tan90 is not defined. Thus the general equation y=a will be the only solution.</p>

<p>Guys I need help with blue book second edition Pg number 337 Q 6 and Pg 340 Q 15. These had pictures attached with them so didn’t know how to write the questions here. Please do answer it only three days remain.</p>

<p>@Jor26029‌ Q6 could you explain with more details. I know the heights are decreasing but the base is increasing right?
Q 15 Thanks but is there no other way like reading the equation based on graph like for example: if f(x)= ax^2 + bx + c
Then positive a and positive c would mean parabola opening upwards with positive y- intercept.
I was just wondering like if plugging -3 in some cases may not work. </p>

<p>@Jor26029‌ thanks for the help :)</p>

<p>i cant find the answer to this question.please help
which of the following is the equation of a line in the xy-plane that is perpendicular to the line with x=2?
a. x=1/2
b. x=-2
c. y=3
d. y=-1/2x
e. y=-2x </p>

<p>answer is c. i got it right but it was more of a guess can some please explain</p>

<p>The line x=2 is a vertical line. The line y=3 is a horizontal line. Vertical lines are perpendicular to horizontal lines. So the answer is C.</p>

<p>So that means that k=3, not 30 correct? Because I set it up using algebra and I got 3 as the value for k but I wasn’t sure if I was right or not…</p>

<p>Can anyone solve this question ??
1,2,3,4…50
Find the 90th digit </p>

<p>From 10 to 50 inclusive there are 2*41 = 82 digits. Add in 1,…,9 and the sequence has 91 digits total. 90th digit is 5.</p>