Quadratic and exponential word problems — Harder example | Math | SAT | Khan Academy

Watch Sal work through a harder Quadratic and exponential word problem.

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[Patrick-kyez]

This question by itself takes up about 10% of the total time given on the SAT math section. smh

[sheikhabd-ul-rehman]

if it's a "calculator" question then it can be done in under 30 seconds.

for CHOICE A : - simply multiply $1.35 with 2400 = $3240

for CHOICE B : - same method as with A, $9.30 × 2400 = $22, 320

for CHOICE C : - $ 10.65 - $9.30 = $1.35
($1.35 ÷ $0.10) × 20 = 270
this 270 is the subscriber decrease and (2400 - 270) = 2130 are new subscribers
income from new subscribers = 2130 × $10.65 = $ 22, 684

for CHOICE D : - same method as C, but no subscribers will be left after such an inflation😅

[pranishuprety]

You are making this problem seem more complicated, Sal

[okelise]

or just make an educated guess based off of what they already charge, which is $9.30. choice a is way too small bc why would a company charge that much less, b is plausible but they're trying to make money so c, which is just a dollar and 35 cents more makes sense, and d is way too high bc they'll lose subscribers

[No-wtmf]

Bruh how are we supposed to get a good score on the SAT going at this pace XD

[jazzydan]

how are you supposed to have enough time to figure this out on the SAT 😫

[hghxp_baby]

or you could've done none of this rubbish and just calculate the decrease or increase in dimes for each option, subtract the respective number of subscribers in correlation to the dimes increased or decreased and multiply the new subscribers with the price and see which option has highest revenue

[homeboi]

Much easier way:

(9.30+0.10x)•(2400-20x)

Solve x=0 (-93 & 120) and take halfway point (or -b / (2a) ), this will get you 13.5, which is how many times the price increases by 10¢, so that’s $1.35, add that to $9.30 to get the same answer of $10.65.

[aqsashafiqrandhawa]

Is that type of questions are come in competitive exams?

[coolthing]

At 2:02, why do we have to divide the absolute price increase by 0.10? What does P-9.30 mean?

[shubhranshrai]

of course -- waste all time on one question!

[salehabegum]

I don't understand any of this math part. Someone please help me.

[sarthaksonawane]

Can anyone explain me 2nd line...plz I don't get it

[conducter]

you should just go by testing each answer at this point