A bag contains only pink, black and yellow marbles. The ratio of pink to black marbles is 8:7.
The ratio of black to yellow marbles is 1:5.
Calculate the percentage of marbles that are black​

The sum of the reciprocal of a positive number and the reciprocal of 2 more than the number is 3/4 equation: the number is

The random variable x is the number of occurrences of an event over an interval of ten minutes. it can be assumed that the probability of an occurrence is the same in any two-time periods of an equal length. it is known that the mean number of occurrences in ten minutes is 5.3. the appropriate probability distribution for the random variable

Identify the number 127 as a rational or irrational. explain