Answer:
r is always between 0 and 1
Step-by-step explanation:
The untrue statement is ...
r is always between 0 and 1
One way you can tell is that it is inconsistent with the true statement |r| ≤ 1.
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<em>Comment on correlation coefficient</em>
The correlation coefficient (r) is the ratio of the covariance of x and y to the product of the standard deviations of x and y. This formula is symmetrical in x and y, so it doesn't matter which data set you call x and which one you call y. Similarly, the units cancel, so r is a unitless number, and the units of x and y don't matter, either.
To answer this you can use a guess and check strategy.
Start with 5 minutes using it (25% lost) and 10 minutes charging (20% gained).
Try 7 minutes using it (35% lost) and 14 minutes charging (28%).
Next, 9 minutes (45%) and 18 minutes(36%).
10 minutes (50%) and 20 minutes (40%). This is the difference.
She used it for 10 minutes and charged it for 20 minutes.
