The following table gives the number of branches and number of plants in the garden of a school. No. of branches `(x)` : 2 3 4 5 6 No. of plants `(f)` : 49 43 57 38 13 Calculate the average number of branches per plant.

The following distribution gives the number of accidents met by 160 workers in a factory during a month. No. of accidents (x) : 0 1 2 3 4 No. of workers (f) : 70 52 34 3 1 Find the average number of accidents per worker.

The following table gives the number of children of 150 families in a village No. of children (x) : 0 1 2 3 4 5 No. of families (f) : 10 21 55 42 15 7 Find the average number of children per family.

The number of telephone calls received at an exchange per interval for 250 successive one-minute intervals are given in the following frequency table: No. of calls (x) : 9 1 2 3 4 5 6 No. of intervals (f) : 15 24 29 46 54 43 39 Compute the mean number of calls per interval.

In the first proof reading of a book containing 300 pages the following distribution of misprints was obtained: No. of misprints per page (x) : 0 1 2 3 4 5 No. of pages (f) : 154 95 36 9 5 1 Find the average number of misprints per page.

The following table gives the numbers of failures of commercial industries in a country during the years 2000 to 2015. Draw a graph illustrating these figure. Calculate the 4 yearly moving averages and plot them on the same graph.

The number of chromosomes in leaf tip cell of plant is 6. The number of choromosoms in each of the 4 cells of its pollen tetrad would be

The variance of the numbers 2, 3, 11 and x is (49)/(4), then the value of x are