1. The table below shows the probability distribution of a random variable X. Find the value of p.

X=x	1	2	3	4	5
P(X=x)	0.2	0.2	0.3	p	2p

2. A fruit stall sells plums. The weights of plums are normally distributed with a mean of 80 grams and standard deviation of 4 grams. Five plums are chosen at random, find the probability exactly three of them weight more than 82 grams.

(2 decimal place)

3. The masses of guavas in a farm are normally distributed with a mean of \mu and a standard deviation,\sigma.The mass of percentage of guava less than 400 g is 15.87% and more than 500 g is 6.88%.Determine the value of \mu and \sigma.