She saves 10 per week.......after 4 weeks, she had 90
so if she started with nothing, after 4 weeks she would have 40.....but for her to have 90, she would have had to have started with (90 - 40) = 50.
Think about it....she starts with 50....and then saves 10 for 4 weeks giving her 40......and now she has 40 + 50 = 90
so ur answer is : Roberta had $ 50 before she started to save money each week
The answer to this question is -154
Even function: f(-x) = f(x). If you replace x by -x you should find the same function.
Odd function: f(-x) = -f(x). If you replace x by -x you find the same function with opposite sign;
Is f(-x) = f(x)?
f(x) = (x+4)² = x² + 8x +16
f(-x) = (-x+4)² = x² - 8x + 16, then it's not an even function
Is f(-x) = -f(x)?
f(-x) = (-x+4)² = x² + 8x + 16 , then it's not an odd function
It is neither an even nor an odd function
She asked her friends, which does not represent a random sample.
She tried to show cause and effect without doing an experiment (which includes simple random sample, control group, treatment, etc).
So the answer is she did not use a random sample, and tried to show cause and effect with an observational study.
