Quantitative Aptitude - Arithmetic Ability Questions

Probability of occurrence of an event, 

P(E) = Number of favorable outcomes/Numeber of possible outcomes = n(E)/n(S)

⇒ Probability of getting head in one coin = ½, 

⇒ Probability of not getting head in one coin = 1- ½ = ½, 

Hence, 

All the 11 tosses are independent of each other.

∴ Required probability of getting only 2 times heads =122×129=1211

We can select atleast one item from 6 different items = 26-1  

Similarly we can select atleast one item from other set of 6 different items in 26-1 ways. 

Required number of ways = (26-1)26-1 = 26-12 = 3969

Let the third subject marks be 'x'
=> Second subject marks = 2x
=> Third subject marks = 4x
Given avg = 224
x + 2x + 4x = 224 x 3
=> 7x = 224 x 3
=> x = 96
Hence, Second subject marks = 2x = 2 x 96 = 192.

Number of non - negative integral solutions =n+r-1 Cr-1 = C223 = 253 

Number of decimal places in the given expression = 8

Number of decimal places in (A) = 8

Number of decimal places in (B) = 9 

Number of decimal places in (C)= 7

Clearly , the expresssion in (A) is the same as the given Expression.

Since 20% i.e 1/5 typists left the job. So, there can be any value which is multiple of 5 i.e, whose 20% is always an integer. Hence, 5 is the least possible value.

Given the average age of couple and their son = 40

=> Sum of age (H +W +S) = 40×3

Let the age of daughter in law at the time of marriage = D years

Now after 10 years,

(H + S +W) + 3×12 + D +12 + 10 = 38×5

178 + D = 190

D = 190 -178 = 12 years

The length of the longest pole which can be kept in a room 12 m long, 4 m broad and 3 m high is

=>  d2 = 122 + 42 + 32 = 13mts.