4. Percents and Iterest

• Theory
  Math: Number Theory - Percents
  Percentages, Interest and More
  
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    Compound Interest Problems
    DS Questions
    PS Questions

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1) Shortcut: Day 1 is 20% = \(1.2=\frac{6}{5}\)*Day 3

Day 3's number must be divisible by 5
That leaves answers B and D

Eliminate B) 5,190: Here, Day 1 is 2+ times greater than B, not 1/5 greater than

Answer D
(If you backsolved, i.e., used answer choice * 6/5, the shortcut would be evident quickly)

2) Equation

Day 1 attendance is 20% greater than Day 3
Day 1 = 1.2*(Day3)
Let x = Day 3 attendance

\(11,418 = 1.2x\)
\((\frac{11,148}{1.2})=(\frac{114,180}{12})=x\)
\(x = 9,515\)

Answer D
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In the depths of winter, I finally learned
that within me there lay an invincible summer.
-- Albert Camus, "Return to Tipasa"

Let a be the attendance of crowd on Day 3.
Day 1 = 1.2a = 6/5a

6a/5 = 11, 418
a = 11,418 * 5/6

No need to perform the division, we can see that 18/6 = 3 so we will get xxx3 *5 thus we are looking for unit digit of 5 in the answer choice thus
D.

Let x be the attendance on Day - 3.

Day 1 attendance = 1.2x
=> 11418 =1.2x

x = 9515

Option D.
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Dhruv
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