i need some help on the following question......

The probability that a glass fiber will shatter during an experiment is believed to follow a poisson distribution. In certain apparatus, it was found that, on average, 7 glass fibers shattered. Determine the probability that, during a single demonstartion of the experiment,

i) two glass fibres will shatter

ii) at most two glass fibres will shatter

im finding it really difficult.

Thank you