Question

If a safety switch has a 1 in 10 chance of how many switches would u need for it to have a 1 in one million chance of failing

Answer 1

The probability that one switch fails is 1 from 10. According to this the probability is 1/10=0.1.

If you need to have only 1 switch from million to fail, this means that you need the probability 1/1000000=0.000001.

In order to have this probability of one switch failing you will need 1000000 (million) switches.