Suppose that for people over 80 years of age there is a 20% chance that a Covid-19 case requires hospitalization. In a random sample of 13 people over 80 years of age that have contracted Covid-19, let X be the number who require hospitalization. Consider the following probability distribution for X.

x	P(x)
0	?
1	?
2	?
3	a
4	0.1535
5	0.0691
6	0.0230
7	0.0058
8	0.0011
9	0.0001
10	0.0000
11	0.0000
12	0.0000
13	0.0000

Find the missing entry that is labelled as 'a'.

Suppose that a group of 13 people over 80 years of age who have contracted Covid-19 are randomly selected, and 4 of them required hospitalization. Is this a significantly high number that would suggest that the given percentage requiring hospitalization (i.e., 20%) is not correct?