20 pts: What factors should be considered when deciding where to add voltmeters and ammeters in a circuit schematic?

Explain why electric current cannot exist if a current doesn't have a voltage source.

The number of passengers who arrive at the platform of a subway station for the 10 am train is a random variable with a mean of 120 and a variance of 16. find the lower bound of the probability that there will be between 100 and 140 passengers (round off to second decimal place).

What happens to an isotope during radioactive decay?