6/21 + 7/21 = 13/21 of the lawn was mowed?
Answer:
Step-by-step explanation:
From the question we are told that
The sample size is n = 15
The level of significance is 
The null hypothesis is 
The alternative hypothesis is 
Generally the degree of freedom is mathematically represented as

=> 
Generally the critical value of
at a degree of freedom of
is

What are you trying to figure out