AP chem question CH 3?

Question

Chromium (atomic mass= 51.9961 amu) had 4 isotopes. their masses are 49.94605 AMU, 51.94501 amu, 52.94065 amu, and 53.93888 amu. the first two isotopes have a total abundance of 87.87% and the last isotope has an abundance of 2.365% what is the abundance of the third isotope? Estimate the abundances of the first two isotopes. - whats the answer and how do u get it.

Answer 1

52 Cr 83.789% Cr is stable with 28 neutrons
53 Cr 9.501% Cr is stable with 29 neutrons
54 Cr 2.365% Cr is stable with 30 neutrons