Answer: 140
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Work Shown:
7/20 = 0.35 = 35% of the 20 players made all five baskets.
If this trend holds up, then we should expect 35% of the 400 people to make all five baskets.
35% of 400 = 0.35*400 = 140
We expect about 140 people will make all five baskets.
Note how 140/400 = 0.35 = 35%
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Through another alternative method, we can solve like this
7/20 = x/400
7*400 = 20*x ... cross multiply
2800 = 20x
20x = 2800
x = 2800/20 ... dividing both sides by 20
x = 140 which is the same result as before