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  • Ball-parking is a technique that helps us to solve problems quickly.

  • Instead of trying to get the perfect result,

  • we make a fast, intelligent guess.

  • Just like in baseball.

  • To score, we don't need to hit the ball perfectly.

  • Often we just need to keep it inside the ballpark.

  • The technique is useful in conversations

  • and is essential to passing certain tests.

  • To watch this video most effectively,

  • grab a pen and paper,

  • and try solving the following two problems as we present them.

  • Just pause whenever you see this sign.

  • Let's start easy!

  • What do you think is the most popular food in the world?

  • Could it be Italian, Japanese,

  • American fast food, or something else?

  • As it is impossible to get an exact answer,

  • let's look at what we maybe already know.

  • In Italy, there are around 50 million people,

  • in Japan about 100 million

  • and in North America about 500 million.

  • But in China or in India there lives over a billion people.

  • Now we can use the process of elimination

  • and make a ballpark estimate that

  • Chinese and Indian food is probably the most popular.

  • Now let's try something a little harder.

  • Imagine that you are doing a complicated math test

  • for something like the GMAT exam.

  • Then you might just 2 minutes to solve complex problems in your head.

  • Maybe something like: The square root of: 5 times the square root of 24,

  • plus 5 divided by, 5 plus 2 times the square root of 6.

  • Then you're given five multiple choice answers:

  • A, B, C, D or E.

  • If we would try to solve it, we would probably run out of time.

  • Ball-parking is now the only option.

  • You can try it on your own

  • or do it with us.

  • Look at the equation. Let's look the first part,

  • the square root of 24.

  • Since the square root of 24 is difficult to calculate in your head,

  • think of a close enough number to the square root of 24

  • that would be easier for you.

  • The square root of 25 comes to mind.

  • To which the answer is 5.

  • Let's now write down the new simpler equation

  • and then again even simpler.

  • Now what about the fraction?

  • It looks hard, but let's try!

  • Even if we don't know what 5 plus 2 times the square root of 6 is,

  • we do know that it's more than 5.

  • So let's write it again and just call the denominator [6.1] “more than 5”.

  • And because 5 divided by anything larger than 5 must be smaller than 1,

  • we can just write “25 plus less than 1

  • or the square root of 25.

  • And that equals approximately 5.

  • Lets now look at the options we were given.

  • Let's look at the equation and each possible choice.

  • A is clear and doesn't look bad.

  • B is 5 plus 2 times the square root of 6

  • which is something like 7 or more.

  • That doesn't look right.

  • C is the square root of something that comes out to be 3 or less.

  • That's too small.

  • What about D?

  • The square root of 120.

  • We don't know that,

  • but we do know that the square root of 100 is 10.

  • Lets just write 10 or more.

  • That looks too high.

  • Last there is E.

  • 5 divided by 2 times the square root of 6.

  • Now for 2 times the square root of 6

  • lets just writemore than 2”.

  • And 5 divided by something that's more than 2

  • also looks too small.

  • Now we use the process of elimination

  • and cross out all the wrong answers to see what's left.

  • A it is.

  • Now it's your turn.

  • Try ball-parking the amount of views

  • that you think this video will have by the end of this year

  • and win your favorite Sprouts gift on Patreon.com/Sprouts

  • We will count all entries submitted by August 31st

  • and announce the winner on the 1st of January.

  • To join, just leave your ballpark figure in the comments below.

  • And if you want, tell us how you did it.

  • Those of you who post later than August 31st

  • will enter next year's round of Sprouts Ballpark Awards.

  • Good luck!

Ball-parking is a technique that helps us to solve problems quickly.

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A2 square root root square ballpark parking divided

Ball-Parking: Get Better Grades by Through Elimination

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    Summer posted on 2021/04/30
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