A rational number is any number that can be expressed as a ratio of two integers. For example, 1.5 is rational since it can be written as 3/2, 6/4, 9/6 or another fraction or two integers. Pi is irrational since it cannot be written as a fraction.
If one student is chosen from a pool of 2444 maie students, of which 102 are aspiring research scientists, the probability that the chosen student student is a future research scientist is
102/2444 = 4.17% (to the nearest hundredth percent)