1. The algebraic sum of deviations from mean is

2. The sum of squares of deviations from mean is

3. An additional observation of 15 is included in a series of 11 observations and its mean remains unaffected. The mean of the series is-

4. The median of a series is 10. Two additional observations, of 5 and 20, are added to the series. The median of the new series will-

5. In a batch of 13 students 4 have failed. The marks of the successful candidates were 41, 57, 38, 61, 36, 35, 71, 50 and 40. Find the median marks

6. From the information given below choose the correct answer-

7. The arithmetic of 9 observations is 100 and that of 6 is 80, the combined mean of all the 3 observations will be

8. . The arithmetic mean of the first N natural numbers is

9. For a symmetrical distribution, Q₁, and Q₃, are 20 and 40 respectively. The value of 50th percentile

10. Pie-diagrams are