The joint distribution of claim frequency and claim severity, conditional on the claim frequency being positive, is given below:

Joint distribution

Claim Size Claim Frequency	100	300	500	1000
1	0.25	0	0.2	0
2	0	0.37	0	0.18

If the probability that the claim frequency is zero is 0.75, determine the variance of the claim frequency.

1. 0.2475
2. 0.5123
3. 0.6625
4. 0.8833
5. 1