SOLUTION: Sally took four test in science class. On each successive test, her score improved by 3 points. If her mean score was 69.5% what did she score on her first test?

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Question 222455: Sally took four test in science class. On each successive test, her score improved by 3 points. If her mean score was 69.5% what did she score on her first test?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Let x = score on first test.

So the next three tests will have scores of x+3, x+6, and x+9 (just add 3 to each previous score). Now average these scores and set that average equal to 69.5 to get:

%28x%2B%28x%2B3%29%2B%28x%2B6%29%2B%28x%2B9%29%29%2F4=69.5


Now just solve the equation above to find 'x' which is the score on the first test. I'll let you do that. Let me know if you still need help.