I am a bit confused with this example.
Suppose that the number of defects on a roll of magnetic recording tape has a Poisson distribution for which the mean λ is known to be either 1 or 1.5. Suppose the prior mass function for λ is $π_λ(1)$ = 0.4, $π_λ(1.5)$ = 0.6 . A collection of 5 rolls of tape are found to have x = (3, 1, 4, 6, 2) defects respectively. Show that the posterior distribution for λ is $π_λ(1 | x)$ = 0.012, $π_λ (1.5 | x)$ = 0.988.