Would really appreciate if someone could help !!!

1) If a large number of samples of size n are taken from B(20,0.2) and approximately 90% of the sample means are less than 4.354, estimate n.

2) i. The random variable has the distribution . Given that and are to independent observations of , find

ii. The random variable is related to by the formula , where and are constants with . Given that , find the values of and , and hence find the values of a and b.

thanks!!