Quantitative Aptitude - Arithmetic Ability Questions

Given total number of students in the class = 21

So each student will have 20 greeting cards to be send or receive (21 - 1(himself))

Therefore, the total number of greeting cards exchanged by the students = 20 x 21 = 420.

Total numbers in die=6

P(multiple of 2)=1/2

P(multiple of 5)=1/6

P(multiple of 2 or 5)=2/3

Almond Selling price = CP(1 + P%/100)

=> CP = 20000, SP = 23000

=> 23000 = 20000 (1 + P/100)

=> P% = 100(23000/20000 - 1) = 15

Then, Olive's P% = 30%

SP for Olive = CP for Sarah = 23000(1 + 30/100) = 29900

Now Sarah wants to earn profit of 8%

=> Sp for Sarah = 29900(1 + 8/100)

= Rs. 32,292.

Profit would be maximum if watches are brought for Rs. 200 and sold for Rs. 425
Profit = Rs. (425 - 200) = Rs. 225
Profit of 9 watches = Rs. 225 x 9 = Rs.2,025.

Let the number of boys = b

Let the number of girls = g

From the given data,

81b + 83g = 81.8(b + g)

81.8b - 81b = 83g - 81.8g

0.8b = 1.2g

b/g = 1.2/0.8 = 12/8 = 3/2

=> g : b = 2 : 3

Hence, ratio between the number of girls to the number of boys = 2 : 3.

4b=6c⇒b=32c and 3a=4b⇒a=43b=43(32c)=2c 

a+b+c=2729 ⇒2c+32c+c=2729 ⇒c=629

 ∴a2+b2+c2=(a+b+b)2-2(ab+bc+ca) 

=(2729)2-22c×32c+32c×c+c×2c 

 =729×29-2×132 c2

= 87