Solution:
It is given that the box contains cards marked with the number 3,4,5,.......,50.So, the total number of outcomes is 50 - 2 = 48.
The probability P(E) of the random experiment as,
P(A)=Number of favorable outcomesTotal number of outcomes
The number of events getting cards of perfect square is,
n(X) = {4,9,16,25,36,49}
⇒Number of favorable outcomes = 6
So, the probability of getting cards of a perfect square is,
P(E)=n(X)Total number of outcomes
⇒P(E)=648
⇒P(E)=18
The probability of getting cards of a perfect square is 18.
Hence, option 3 is the correct answer.