I am trying to do the following question:
Number 24 and number 42 buses arrive independently at the corner of Mayeld Road at a random rate of 3 and 4 per hour respectively. You arrive at the bus stop at 10 a.m. What is the probability that it takes at least 20 minutes for a bus (either the 24 and 42 bus) to arrive?
I am kinda of stuck on how to start it. So I've learned about Uniform distribution, normal distribution and exponential distribution. I actually not really sure which one to use here. Could you also explain what sort of problems to apply each distribution to?
If I set up a random variable, what should it denote? The number of minutes pass 10 for a bus to arrive? Or that the 42 and 24 bus arrive?