To find the upper quartile, we first apply the following equation:
![Q=(3)/(4)(n+1)](https://img.qammunity.org/2023/formulas/mathematics/college/e9mtl0v23frja0ghgs7tnk4ep97i0iysoh.png)
Where n is the size of the dataset. In this case, there is 10 numbers, then:Q
![Q=(3)/(4)(10+1)=(3)/(4)(11)=8.25](https://img.qammunity.org/2023/formulas/mathematics/college/g4nzar1hcr7oijjhgvlhj16v7rwg80e2bz.png)
Then the upper quartile is the 8th number in the data set. The numbers must be ordered:
![17.4,25.4,26.6,27.1,27.6,28,31.8,35,39.5,40.1](https://img.qammunity.org/2023/formulas/mathematics/college/1qhnppri2049tj9pk04aa369ej8d2uff4o.png)
The 8th number is 35. Hence the answer is C. 35