you should be using a hypothesis test - One sample T test.
The answer is given below.
Test of mu = 9.7 vs not = 9.7
The assumed standard deviation = 1.17
N Mean SE Mean 90% CI Z P
21 9.87000 0.25531 (9.45004, 10.28996) 0.67 0.506
since P value is greater than 0.05 we accept the null hypothesis that the population mean equals 9.7