3/5 is the correct answer for sin s
Each term is equal the preceding term plus 3. Therefore the next term is 13 and the difference is +3.
Correct answer is: actual wingspan of airplane is 6 inches.
Solution:-
We are given that wingspan is 'a' feet and tail span is 'b' feet in a scale drawing.
And we are also given that tail span is 2 inches that is b=2 inches and 
Let us plugin the b value in above equation.

Multiplying with 2 on both sides.
a=3X2=6 inches.
Hence actual wingspan of airplane is 6 inches.