Let number of students in n, where n is a two digits prime number, whose both digits are also prime. Again minimum earning of student is x, then maximum earning of the student is (x + 45). Now, total stipend of n students = 50n and total stipend of minimum and maximum earning students = x + x + 45 = (2x + 45) Total earning of remaining students = 50n – (2x + 45) ATQ, Average stipend of reamining students = 50 – 1 = 49 Total earning of remaining students = 49(n – 2) ∴ 50n – (2x + 45) = 49(n – 2) 2x – n = 53 n = 2x – 53 As, 42 ≤ x ≤ 47 for x = 45, x = 2 × 45 – 53 = 90 – 53 = 37 Here '37' is a prime number, also its two digits 3 and 7 are prime. So, number of students = 37.