Answer:
x = 39.1
Step-by-step explanation:
To find the mean, add up all the data points and then divide by the number of data points
(31.7+ 42.8+ 26.4+ x)/4 = 35
Multiply each side by 4
(31.7+ 42.8+ 26.4+ x)/4*4 = 35*4
(31.7+ 42.8+ 26.4+ x) = 140
Combine like terms
100.9+x = 140
Subtract 100.9 from each side
x = 140-100.9
x = 39.1
