Activity 2

 For question 1, we can see the three pictures below. They prove that the statement is true.

 7+2+2=13

 14+3+10=27

 18+19+3=40
For question 2, we can see the two pictures below.

 As you can see, the direction in Spontaneous emission is odd.
For question 3, the time is not constant to excite.
For question 4, the direction in stimulated emission is the same. You can see the two pictures below.

For question 5, we can find that when the pumping level is 70, n2 is smaller than n1. When the pumping number is 80, n2 is bigger than n1. Thus,we guess the pumping level is 75. Check the pictures below.

 For Question 6, we find that the direction is odd at the result of Spontaneous emission.