Answer: Our required probability is 0.058.
Step-by-step explanation:
Since we have given that
Number of students in A = 5
Number of students in B = 8
Number of students in C = 10
Number of students in D = 12
Total number of students in all = 5 + 8 + 10 + 12 = 35
So, we need to find the probability that one student will choose A , 1 student will choose B, 2 will choose C and 3 will choose D.
So, it becomes,
[tex]\dfrac{^5C_1\times ^8C_1\times ^{10}C_2\times ^{12}C_3}{^{35}C_7}\\\\=\dfrac{5\times 8\times 45\times 220}{6724520}\\\\=\dfrac{396000}{6724520}\\\\=0.058[/tex]
Hence, our required probability is 0.058.