Quantitative Aptitude - Arithmetic Ability Questions

Number of positive integral solutions =  n-1Cr-1 = C220 = 190

Total number of students = 54 x 30
When arranged in rows of 45, number of rows formed are,
54x3045 = 36.

As we know that a week has 7 days,

k weeks k days = (7k + k) days = 8k days.

Let Rama's age 8 years ago be x years and mother's age 8 years ago be 5x

      years

Hence, present age of Rama =  years

Probability between z = 0 and z = 3.01 is given by

P(0<z<3.01) = P(z<3.01) - P(z<0)

Reading from the z-table, we have

P(z<0) = 0.5

P(z<3.01) = 0.9987

Hence, P(0<z<3.01) = 0.9987 - 0.5 = 0.4987.

Let the number of students in classes A, B and C be P, Q and R respectively.
Then, total score of A = 83P, total score of B = 76Q, total score of C = 85R.
Also given that,
(83P + 76Q) / (P + Q) = 79
=>4P = 3Q.
(76Q + 85R)/(Q + R) = 81
=>4R = 5Q,
=>Q = 4P/3 and R = 5P/3
Therefore, average score of A, B, C = ( 83P + 76Q + 85R ) / (P + Q + R) = 978/12 = 81.5

Let the cost price of the item = Rs. 50

Sold at 10% loss => for Rs. 50 loss  S.P = Rs. 45

From the  given data,

25/2 % gain if it is sold at Rs. 9 more

56.25 - 45 = 9

=> 11.25 = 9

=> 22.5 = 18

=> 45 = 36

=> 50 = ?

=> C.P = 50 x 3645 = 40

Hence, the Cost price of the item = Rs. 40.