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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.

• 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.

• Try ball-parking the amount of views

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

• 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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