Step 1: From statement I, the ratio of the present ages of P and Q is 3:4. Let the present ages of P and Q be \( 3x \) and \( 4x \), respectively.
Step 2: From statement II, the ratio of the present ages of Q and R is 4:5. Let the present ages of Q and R be \( 4y \) and \( 5y \), respectively.
Step 3: We have two variables \( x \) and \( y \), and no further relationship is provided between \( x \) and \( y \). Therefore, we cannot determine the ratio of P’s and Q’s ages four years ago with the information given in both statements. Thus, the answer is \( \boxed{{C}} \).
Four students of class XII are given a problem to solve independently. Their respective chances of solving the problem are: \[ \frac{1}{2},\quad \frac{1}{3},\quad \frac{2}{3},\quad \frac{1}{5} \] Find the probability that at most one of them will solve the problem.
Two persons are competing for a position on the Managing Committee of an organisation. The probabilities that the first and the second person will be appointed are 0.5 and 0.6, respectively. Also, if the first person gets appointed, then the probability of introducing a waste treatment plant is 0.7, and the corresponding probability is 0.4 if the second person gets appointed.
Based on the above information, answer the following