List I- (Statistical term)  | List II-(Description)  | ||
|---|---|---|---|
A  | Statistics  | I  | Numbers which occur frequently in population  | 
B  | Mode  | II  | Arithmetic average  | 
C  | Frequencies  | III  | Calculus of observation  | 
D  | Mean  | IV  | Value of the item that has highest frequency  | 
The following table shows the ages of the patients admitted in a hospital during a year. Find the mode and the median of these data.
\[\begin{array}{|c|c|c|c|c|c|c|} \hline Age (in years) & 5-15 & 15-25 & 25-35 & 35-45 & 45-55 & 55-65 \\ \hline \text{Number of patients} & \text{6} & \text{11} & \text{21} & \text{23} & \text{14} & \text{5} \\ \hline \end{array}\]
Find the mean and mode of the following data:
| Class | 15--20 | 20--25 | 25--30 | 30--35 | 35--40 | 40--45 | 
| Frequency | 12 | 10 | 15 | 11 | 7 | 5 |