John is thinking of a number in the hundred thousands. the first digit is equal to the number of digits in the number. the number has twenty tens and twice as many thousands. the number of ones is an odd number that os less than 5 and greater than the digit in the hundreds place. what is johns number ?

Among the most famous of all meteor showers are the perseids, which occur each year in early august. in some areas the frequency of visible perseids can be as high as 40 per hour. given that such sightings are poisson events, calculate the probability that an observer who has just seen a meteor will have to wait at least five minutes before seeing another.