Assume X is an exponential random variable with parameter lambda.
a) Find the method of moments estimator for lambda.
b) Use the estimator to estimate lambda and variance from the following data:
{0.107, 0.279, 1.277, 0.656, 0.051, 1.337, 0.175, 0.197, 0.119, 0.029, 0.103, 1.962, 0.020, 0.051, 0.474, 0.048, 1.451, 0.251, 0.371, 0.049}