Find the mean of each of the following distributions :

(i)

xi	10	15	20	25	30	35	40	Total
fi	4	6	8	18	6	5	3	50

(ii)

xi	12	13	14	15	16	17	18	Total
fi	1	3	4	8	10	3	1	30

(iii)

xi	50	75	100	125	150	175	200	Total
fi	12	18	50	70	25	15	10	200

A small indoor greenhouse (herbarium) is made entirely of glass panes (including base) held together with tape. It is 30 cm long, 25 cm wide and 25 cm high.

(i)    What is the area of the glass?
(ii)    How much of tape is needed for all the 12 edges?

Parveen wanted to make a temporary shelter for her car, by making a box-like structure with tarpaulin that covers all the four sides and the top of the car (with the front face as a flap which can be rolled up). Assuming that the stitching margins are very small, and therefore negligible, how much tarpaulin would be required to make the shelter of height 2.5 m, with base dimensions 4 m × 3 m?