How many numbers of the form 2^n – 1 and less than 2000 are prime?

Two dice each numbered from 1 to 6 are thrown together. Let A and B…

Two dice each numbered from 1 to 6 are thrown together. Let A and B…

An urn contains one black ball and one green ball. A second urn contains one…

An urn contains one black ball and one green ball. A second urn contains one…

What is the most probable number of successes in 10 trials with probability of success…