Explanation for Question 38 From the Math (Calc) Section on the Official Sat Practice Test 10
Now looking at number 38, we're still talking about the Falcon, 2 right? And it dove at its maximum speed for half of a mile to 3 catch prey. How many seconds would the dive take? 4 So remember that they can go 200 miles per hour. 5 Um, but they only dove for half of a mile, 6 right? So we can write a proportion to try to figure out how many 7 hours they would have dove if they do for half of a mile instead 8 of 200 miles. Right? So now we've got half of a mile and we're 9 going to try to solve for the time it took them to take in 10 hours and then we will convert that to seconds. 11 Right? So we're just going to solve for X here by cross multiplication and 12 the units no longer matter once you do that. 13 Right? So you've got 200 X is equal to 0.5 to 14 solve for X. I simply need to divide by 200. 15 So we get X as 0.5 divided by 200. 16 I'll plug that in my calculator. And I see that, 17 that means that they went for 0.0 0, 2, 5 of an hour, 18 but we want in seconds. Right? So I need to convert this to seconds. 19 And so this is kind of like the last equation where I'm going to 20 want to multiply by conversion factors. 21 I want my hours to cancel. So I put my minutes on the top 22 and I'm still not interested in minutes. So I'll put my minutes on the 23 bottom and my second on the top here. 24 So now all I need to do is multiply across 0.0 0 2, 5 25 times 60 times 60. And that gives me nine seconds.
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