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1 
What is the largest prime factor of 255? 

A. 
255 

B. 
15 

C. 
5 

D. 
17 

E. 
51 
See Answer & Explanation
Lets Discuss
Correct answer is : D
Explanation A: 255 is divisible by 3, 5 etc so not a prime number.
B: 15 is divisible by 3 and 5 so not a prime number.
C: 5 is not divisible by any other numbers and is a prime number but let's explore other options also.
D: 17 is not divisible by any other numbers and is a prime number.
E: 51 is divisible by 3 and 17 so not a prime number.
Now we have 5 and 17 which are the prime factors of 255 and obviously 17 is larger.
Hence option D 17 is the correct answer.
2 
Determine the value of x in expression 8^{2x4 }= 16^{x }. 

A. 
3 

B. 
6 

C. 
2 

D. 
4 

E. 
8 
See Answer & Explanation
Lets Discuss
Correct answer is : B
Explanation Let's rewrite the expression as
(2^{3})^{2x4} = (2^{4})^{x}
=> 2^{3(2x4)} = 2^{4x}
By comparing both sides we can have
3(2x4) = 4x => 6x  12 = 4x => 2x = 12 => x = 6
3 
If a car is moving at a speed of 54 kilometer per hour, how many meters does it travel in one second? 

A. 
10 

B. 
15 

C. 
20 

D. 
25 

E. 
30 
See Answer & Explanation
Lets Discuss
Correct answer is : B
Explanation If we convert 54 KM/H to meter/second then our problem is solved.
We know that 1 KM = 1000 meters and 1 hour = 60x60 seconds
Hence 54 KM/H = (54 x 1000) / (60 x60) m/s
=> 54 x (5 / 18) m/s => 15 m/s
Tips: It is always good and short to multiply by (5 /18) to convert a number in KM/H to meter/second .
4 
If p pencils cost c cents, how many pencils can you buy for d dollars? 

A. 
dp/100c 

B. 
100dp/c 

C. 
100cdp 

D. 
100cd/p 

E. 
cdp 
See Answer & Explanation
Lets Discuss
Correct answer is : B
Explanation we know that c cents can buy p pencils
therefore 1 cent can buy p/c pencils.
And 1 dollar = 100 cents
therefore d dollar = 100d cents
so number of pencils bought in 100d cents is => 100d x (p/c) => 100dp/c
5 
What is p divided by p% of p? 

A. 
p^{2}/100 

B. 
100/p^{2} 

C. 
100p 

D. 
p/100 

E. 
100/p 
See Answer & Explanation
Lets Discuss
Correct answer is : E
Explanation Let's rewrite the question in expression form and solve
p / (p% of p)
= p / (p/100 x p)
= p / (p^{2}/100)
= 100p / p^{2}
= 100/p