#grid-in

[pwnthesat]

The blue book section 3 number 11 page 834 Thanks

Draw it carefully, in stages.

Here are A and B, 24 units apart:

C is the midpoint of A and B, so draw that next:

The next thing you know is that D is the midpoint of AC, so draw that:

Now you just have to draw E. You know it’s a distance of 5 away from D, which means it could go in one of two places (both shown in red dots below).

So there you have it. Point E will either be 1 or 11 away from point A.

[pwnthesat]

For a grid in question, if the answer is $5.50, can you grid in 5.5? or must you grid in 5.50?

I don't have a definitive answer here—I don't know if I've ever seen a dollar amount answer end in 0 like that. Have you?

My default would be to add the zero just to be safe.

[pwnthesat]

How do we answer p953 in the blue book q 15 without using tan/cos/sin?

ABE is a 30º-60º-90º right triangle. You really should have those side ratios memorized, but if you don't you should at least remember that they're given to you in the beginning of each math section. 

Since its short leg is 8, it's long leg, BE, is 8√3. BE is also a side of the square, so you can find the square's area by squaring 8√3.

(8√3)^2 = 192

[pwnthesat]

A grocery customer spent a total of $9.60 for ground beef and coffee. The coffee cost 2 times as much per pound as the ground beef, and the customer bought 3 times as many pounds of ground beef as pounds of coffee. How much, in dollars, did the customer spend on coffee?

Yeah, this one sucks. To break it down, think for a minute about what the most basic unit is. Seems to me like everything can be defined in terms of the price of ground beef by weight, right? Check it out:

Say the price of a unit of ground beef is x. Then the price of a unit of coffee is 2x. 

Now here's the tricky part. The customer buys 3 times as much ground beef as he does coffee. So say he buys 3 units of beef (cost: 3x) and one unit of coffee (cost: 2x).

So he spent 3x + 2x = 5x on groceries, and that came to $9.60. A little quick division tells us that x = $1.92. Since 2x was the amount he spent on coffee, we can conclude he spent $3.84 on coffee.

[pwnthesat]

official sat practice test 2012-13 , section -6 Q 18. Sorry im unable to include the pdf of the question paper but it is available if u jst type it on google.

[Link to the test can be found here]

Draw a line up from point T to cut the figure into two rectangles. The one on the right has an area of 14, since it's twice the area of the triangle you're given.

Since PT is 2/5 of PS, TS must be 3/5 of PS. Which means the rectangle you just drew, area 14, must be 3/5 of the whole rectangle. Use a proportion to solve:

[pwnthesat]

Test 2 Section 5 - #17 (page 468) I really don't understand the t-20 part. Please explain. Is this common in SAT problems?

This is not an uncommon question type on the SAT, but a question like this will often be multiple choice, which will make it susceptible to plug in or backsolve. In other words, you're fairly likely to see a question of this type again, but it's less likely that you'll have to solve it with algebra.

Think about how you'd write an algebraic expression for a 60-minute call on carrier A. It's $1.00 for the first 20 minutes, and then $0.07 for each minute after—the first minute you pay 7 cents per minute for is the 21st minute, but then you'd be paying 7 cents per minute all the way up to the 60th minute. You'd pay 7 cents per minute for 40 minutes. So a 60-minute call would be $1.00 + (40)($0.07) = $3.80.

That's where the t – 20 you refer to comes from. It's a 60-minute phone call we're calculating above, but we multiply the 7 cents by 40, 20 fewer minutes than the total length of the call.

So the expression we write for the cost of a t-minute call on carrier A is:

We're going to set that equal to the expression we write for a call on carrier B:

So let's solve! (I'm gonna stop using dollar signs, if that's cool with you.)

[pwnthesat]

I did not understand q no 15 pg 530 from the other website. Please help me with that :(

Hmm. I'll give it a shot.

Here's what you start with (not to scale):

You know a few things about bisectors, right? Don't just start drawing all over this thing, or it's going to get very busy very quickly, and make it harder for you to solve. Instead, look through the bisector information you have and don't fill anything in until you know one half of something that's being bisected. OK?

That's why we want to start with the fact that segment OB is a bisector...because since we know the measure of angle AOB, we'll be able to fill in angle BOD:

So far so good? What's the bisector we should look to next? Segment OD bisects the whole thing, doesn't it? Since we know the measure of angle AOD now (it's 80º), that'll help us a bunch:

OK. Now remember what we're actually looking for here. We want the measure of angle BOE, right? We've got it. Since angle FOD measures 80º and angle FOE measures 30º, angle EOD must measure 50º. 

We already know angle BOD measures 40º, so angle BOE is 40º + 50º = 90º. 

Note that we never really needed to use the fact that segment OC is a bisector--this question gives more information than is needed. The SAT doesn't usually give a ton of extra info, but once in a while you'll get stuff you don't need.