For drawing a frequency polygon of a continuous frequency distribution, we plot the points whose ordinates are the frequencies of the respective classes and abscissae are respectively :

1. upper limits of the classes

2. lower limits of the classes

3. class marks of the classes

4. upper limits of preceding classes

Median of the numbers 4, 4, 5, 7, 6, 7, 7, 3, 12 is

1. 4

2. 5

3. 6

4. 7

In a data, 10 numbers are arranged in ascending order. If the 8th entry is increased by 6, then the median increases by

1. 0

2. 2

3. 3

4. 6

Find the mean and the median of the following set of numbers :

8, 0, 5, 3, 2, 9, 1, 5, 4, 7, 2, 5.