I wanted to ask that which formula to use in a question of Statistics Class 11?

I am confused.. sometimes we use discrete data formula and sometimes we use the continuous frequency formula...

How to know?

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6. An electric kettle of 500 heat water everyday for 2 hours . Calculate the number of unit of elect med y it in 10 days.

Prove that [a, b, c, d] = [a, b, c] + [a, b, d]

If Salary for February month  is 50000  so i usually deduct 1303 as TDS and Credit 48697 as salary to my Staff but this time I have Deducted 20000 as Advance which is taken on October and also Deducted 1303 tds and Credited 28697 as salary this way of calculation is correct or wrong ? When i deduct Advance salary amount will become less then the tds amount will differ or not?

• I want to learn indirect and direct taxes 
  

1. 13.3 exresis Q.number 8

sales tax calculation  in construciont work

15.3 Q.number 5

rs agarwal important question

in  which exercise whose questions in  which exercise whose questions are most important for examinations

are most important for examinations