X brand of batterys have a mean charge lasting time of 90 minutes and a standard deviation is 35 minutes but are not normally distributed.

What is the probability that a randomly selected battery lasts more than 100 minutes?

I can't use a t-test for only one battery because there are 0 degrees of freedom. I can't use a z-test because the population is not normally distributed. If anyone could explaine how to solve this problem I would really appreciate it.