Quantitative Reasoning One-Liner PDF
Q. What is the 101st term of the sequence: 1, 4 7, 10, …. ?
Answer: 301
Solution
This is an arithmetic sequence with common difference of 3. The first element is 1, and total elements are 101. So, a1 = 1, d = 3 and n = 101. So, by using the formula of nth term of an arithmetic sequence, we have
Q. What is the sum of the sequence: 10, 20, 30, 40, …. , 1000 ?
Answer: 50,500
This is an arithmetic sequence with common difference of 10. The first element is 10, and total elements are 100 (Total elements in the sequence 10, 20, 30, … , 1000 are 100). And, the last element is 1000. So, a1 = 10, an = 1000, d = 10 and n = 100. So, by using the formula for the sum of n elements of an arithmetic sequence, we have
Q. What is the solution of the equation

Answer: 
Solution

Q. If
, then what is the value of the function

Answer: 12
Solution

Q. What comes next in the sequence: 2, 3, 7, 23, __?
Answer: 87
Solution
Multiply the element with 4 and then subtract 5 to obtain the next term

Q. What is the value of
in the equation

Answer: 3
Solution

Q. How many feet there are in 4.5 meters? If 1 meter = 3.281 feet.
Answer:(C) 14.76
Solution

3.281 ⇒ three digits after decimal
4.5 ⇒ one digit after decimal. Hence,
14.7645 ⇒ (3+1=4 digits after decimal)
Q. If person-A can complete a particular work in 10 days and person-B can completes that same work in 12 days. How much time it will take if they work together?
Answer: 5 days and 11 hours
Solution

Q. A student obtained the marks: 60, 50, 70, 65 and 85 in Physics, Chemistry, Statistics, English and Biology respectively, and 0 marks in Mathematics. What the average marks he obtained?
Answer: 55
Solution
Average is calculated as, sum of elements divided by number of elements, that is
Q. What are values of and
in the following pair of equations

Answer: and
Solution

Q. What is the geometric mean of the numbers: 2, 4 and 8?
Answer: 4
Solution
By applying formula for calculating geometric mean, we have

Q. What is the 71st term of the sequence: 4, 7, 10, 13, …. ?
(A) 214
(B) 216
(C) 218
(D) 220
Answer: 214
Solution
This is an arithmetic sequence with common difference 3, and the first term is 4. By applying, formula for finding the nth term of an arithmetic sequence we have

Q. What is the sum of the sequence: 5, 10, 15, …., 5000 ?
(A) 250,2200
(B) 250,2300
(C) 250,2400
(D) 250,2500
Answer: 250,2500
Solution
This is an arithmetic sequence with common difference 5, the first term is 5, and the last term is 5000. By applying, formula for finding the sum of the n terms of an arithmetic sequence, we have

NOTE: There are 1000 terms from 5 to 5000, so n = 1000.
Question:
If x is an odd number, which of the following is definitely even?
A. x²
B. x(x + 1)
C. x + 2
Time to test-drive each option:
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A: An odd number squared is still odd (3² = 9). Nope.
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B: Odd × Even (x + 1 is even) = Even. Ding ding ding!
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C: Odd + 2 = Still odd (5 + 2 = 7). Not it.
Answer: B
Question:
Solve for x:
x² – 5x + 6 = 0
Let’s not overthink it.
This is a classic “factor me!” problem.
Try to break it into two brackets:
-
(x – 2)(x – 3) = 0
Set each part to zero:
-
x = 2 or x = 3
Answer: x = 2 or 3
Question:
What’s the area of a circle with a radius of 7?
Use this formula:
Area = π × r²
= π × 7² = π × 49 = 49π
No need to punch numbers into a calculator unless they ask for a decimal.
Answer: 49π
Question:
A phone goes from $80 to $100. What’s the percent increase?
Let’s break it down:
-
The change = 100 – 80 = $20
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Now compare: 20 is what percent of 80?
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20 ÷ 80 = 0.25 → That’s 25%
Answer: 25% increase
Tip: formula:
(New – Old) ÷ Old × 100
Question:
You’ve got 5 liters of a 50% alcohol solution. How much of a 20% solution should you add to get a 30% blend?
Think it through:
-
You already have 5 liters with 50% alcohol = 2.5 liters of pure alcohol
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You’re adding x liters of 20% alcohol = 0.2x
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Total solution becomes (5 + x) liters
-
Total alcohol: 2.5 + 0.2x
Set up the equation:
(2.5 + 0.2x) / (5 + x) = 0.3
Solving that gives you: x = 10
Answer: Add 10 liters of the 20% solution
Question:
If 3 < 2x + 1 < 9, what values can x take?
Split it up:
-
3 < 2x + 1 → Subtract 1 → 2x > 2 → x > 1
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2x + 1 < 9 → Subtract 1 → 2x < 8 → x < 4
So x has to be between 1 and 4
Answer: 1 < x < 4
Question:
A bag has 3 red and 2 blue balls. You pick one at random. What’s the chance it’s red?
So simple it hurts:
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Total balls = 3 + 2 = 5
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Red balls = 3
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So, chance of red = 3 out of 5 = 3/5



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