Solving a problem in physics section 36 paragraph 29 qu

29. An electron with energy E = 30 eV encounters infinitely extended rectangular potential threshold height U0 = 31 eV. Determine the relative density of the electron probability η stay in the area at a distance of 2 x = 100 pm from the border regions (ie the ratio of the probability density of the electron residence at x = 100 pm to the probability density of his stay in the border area at x = 0).