Mean = total score : frequency
mean x frequency = total score
so
83 = total score : 6
83 × 6 = total score
498 = total score
so the sum of the 6 test scores is 498
88 times 1.8 would be 158.4! Hope this helps!
An arithmetic sequence starts with one number and you add the common difference to the previous term to get the current term
So...
f(x)=mx+b
m=common difference
b=starting point
f(11)=125=11m+b
-
f(1)=5=1m+b
--------
120=10m
Divide both sides by 10
12=m
Your common difference is 12.
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