when continous series is given and Y variable is given in discrete series. how can we find correlation?

In such a case,we can find the mid values of class intervals of X(Continuos variable) and apply the formula to the two variables.

an example:

C.I.	Mid-values (X)	Y	XY
0-10	5	35	175	25	1225
10-20	15	45	675	225	2025
20-30	25	60	1500	625	3600
30-40	35	70	2450	1225	3900
40-50	45	80	3600	2025	6400
	sum = 125	sum = 290	sum = 8400	sum = 4125	Sum = 18150

r = 0.997