Help me with these Math questions

MyRealName · October 15, 2013, 10:43pm

Answers are
C
B
C
E
C
B
A
A
33
608
A

If you don't feel like doing them all and explaining, that's fine if you do 1 or 2 or 3.

I've been getting an unusual amount of Math questions wrong recently, I don't know why.

TheAnomalist · October 15, 2013, 10:55pm

For number 1.

Since (0.5, 3) is the maximum, you know the radius is 3. Also, you can deduce that the center of the circle is (0.5, 0). [move down 3 units since radius is 3]

Now, since you know the radius and the center’s X coordinate, you simply subtract 0.5 by 3 (radius) to find the left-“est” point which is negative 2.5.

TheAnomalist · October 15, 2013, 10:58pm

For number 2.

Draw a hexagon and count all the diagonals and the sides.

TheAnomalist · October 15, 2013, 11:06pm

For number 3.

Because you know ORST is a square, you can deduce that T is (10,0).
To find the base of the triangle, subtract the lengths: 10 - (10-2a)= 2a

Since Q is (10,a), QT is a.

2a times a is 2a^2.
Then divide by 2 since it is a triangle (QPT)

a^2 is the area of triangle.

Given that the ratio of the AREA of the triangle to the AREA of the square
Set up a proportion: a^2/100=1/5

The 100 comes from 10*10=

Solve for a.

007Science · October 16, 2013, 12:16am

Question 4, the letters can be pretty confusing but take it in parts.

If a member sells x bars in a day then in 5 days a member will sell 5x bars.
1 member in 1 day= x
1 member in 5 days=5*x

so 3c members will sell 5x * 3c= 15xc in 5 days
1 member in 5 days= 5x
3c members in 5 days =3c* 5x

one box has c bars in it so the amount of boxers will be 15cx/c

c candy bars= 1 box
1 candy bar= 1/c box
15cx bars= 1/c * 15cx boxes
so 15x boxes

007Science · October 16, 2013, 1:14am

Question 6, Again take them in parts. So much easier and less confusing :S

The first part is multiples of 5 that are less than 1000.
I took a range of 1-100(5,10,15,20…) and got 20 integers. It’s gonna repeat the same process for the next 100 and beyond. So 105-200(105, 110,115,120…) is also going to have 20 integers. etc

So in all 200 integers

The next part is 3 times an even integer. so in other words what they are saying is
odd * even= even. So we only want the even integers out of the 200 integers.

Automatically we know that half of the integers are even and half are odd (5=odd,10=even,15=odd,20=even…) again it repeats it’s self. odd,even,odd, even.

So we are now down to 100 integers. From these hundred even integers we only want the ones that are multiples of 3 because they said 3 times an even integer. Again, I took a range of 1-100 to find these as it’s easier to remember. So 3,6,9,12,15… etc and got 33… Obviously 3,6,9 and 15 are odd but if you multiply them by 10 (310=30, 610=60, 9*10=90) they will be even integers that are multiples of 3 and 5.

Or in short look for even multiples of 15

it’s even cause they said 3* even integer. odd * even=even
multiples of 15 because it must be a multiple of 5 and they said 3 times as well

007Science · October 16, 2013, 1:45am

Question 7, again I emphasis on taking them in parts. Easier to read and understand.

Firstly they said a and b are integers so we know they are whole numbers and not fractions.

Also when a is added to b it must be less than 1000.

The major point is a/b=0.625… a/b could be considered a fraction so it’s best to change 0.625 into a fraction as well and equate them.

I’m not sure what calculator you’re using but mine has a function to switch between fractions and decimals… 0.625/1 is a fraction and as easy on the eyes numbers equal 5/8. so 0.625 as a fraction is 5/8…

so when you equate them we know that a is a multiple of 5 and b a multiple of 8. together a+b(5+8) is a multiple of 13.

As they noted it must be less than 1000. I always like to start with numbers that are multiples of 10 as it’s an easier number to remember/work with (depending on the question)

So through trial and error I’d start off w 100 and get 1300 which is too big
I’d arrive at 13 * 70 which is 910 but always make sure that is the number you’re looking, you wanna get as close as possible to 1000.

I’d multiply it by numbers in the 70’s to get as close as possible to 1000. 13*76= 988

So a + b= 988

remember that b is a multiple of 8 so the number we are looking for has to be a multiple of 8.

It’s important to note that a fraction is also a ratio. so a:b is in a 5:8 ratio.
all we want is b so we multiply 8/13 * 988 to get 608

007Science · October 16, 2013, 2:07am

Question 8,

if you look at ABD you could tell it’s an equilateral triangle. So that means if AB=3, AD and BD is 3 as well. Since D is the midpoint of AC, AD will be half of AC. Which will mean AC= 2* AD= 6

Now look at triangle BDC, we know that BD and DC are equal which would make that triangle an isosceles.

DC is equal to 3 because it is half AD (D is the midpoint)

Look at the angle by D, it’s 60. Remember angles on a straight line adds up to 180 so angle BDC is (180-60=120)

Which leaves a remaining 60 in triangle BDC but remember it is an isosceles triangle. So the other two angles would be 30, 30. Fill in the angles on the diagram so you can see it.

Now Ignore line BD and you will see that triangle ABC is a 30-60-90.

Based on the special triangles rules it is x-x root 3-2x. x being opposite 30, x root 3 opposite 60 and 2x opposite 90… write it in…

we want to find the angle opposite the 60 degrees which is x root 3 and we know that x=3.

so x root 3= 3 * root 3

007Science · October 16, 2013, 3:03am

Oh and number 5.

draw 3 circles on a paper and you would get none

BUT they asked for the MOST and that is the least.
So draw two circles and make sure they overlap/intersect so you would get two points of intersection and exactly where they intersect start to draw another circle.

so the top of the other circle is on the first intersection and the the bottom of that same circle on the next point of intersection. So you will end up w two. You should get a drawing where it kinda looks like an eye, creepy :|

xiggi · October 16, 2013, 3:24am

For 7, there is no need to plug numbers.

.625 is 5/8

Divide 1000 by 13, and you get 76. Forget the remainder.

The answer is 76*8 or 608.

Ps. Google the problems!

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