Detailed Instructions: The task is to generate the correct answer for a given math problem.
Q: Problem: a boy perform 5 times a reaction and his reading are 2 , 2.1 , 2 , 2.2 but unfortunately 5 th reading clearly not visible because a drop of chemical fall onto it . but luckily he have mean of all reading which is 2 . please help him in finding 5 th reading .
A:
1.7