Answer:
the combined mean and standard deviation for these exams are
mean = 5.84
standard deviation = 1.766
Explanation:
Given that;
mean score and standard deviation of AP biology was;
x'1 = 3.10, S1 = 1.05
mean score and standard deviation of AP US History was;
x'2 = 2.74, S1 = 1.42
Now combined mean = x'1 + x'2 = 3.10 + 2.74 = 5.84
standard deviation combined = √( S1² + S2²)
= √( (1.05²) + (1.42)²)
= √( 1.1025 + 2.0164)
= √3.1189
= 1.766
Therefore
the combined mean and standard deviation for these exams are
mean = 5.84
standard deviation = 1.766