Following data reveals the usage of units of electricity by different consumers of a certain area:

Units consumed	1 -50	51 - 100	101 - 150	151 - 200	201 - 250	251- 300
Number of   Users (Frequency)	24	68	104	126	84	44

Find the following for given data

1. Arithmetic Mean.       
2. Median
3. All Quartiles.
4. 3^rd and 9^th Deciles.
5. 18^th and 76^th Percentiles.