AP Stat just 2 problems?

Test Preparation AP Mathematics & Computer Science
1

<p>I need help on understanding just two problems please..</p>

<p>A consumer group collected information on standard color TVs (no HDTV or large screen sets). They created a linear model to estimate the cost of a TV (in dollars) based on the screen size (in inches) Which is the most likely value of the slope of the line of best fit?</p>

<p>A.) 0.15
B.) 1.5
C.) 15.0
D.) 150.0
E.) 1500.0</p>

<p>I thought it was impossible to answer but answer is C.
Can you explain why its C thou? i didn't really understand in class.</p>

<p>Education research consistently shows that students from wealthier families tend to have higher SAT scores. The slope of the line that predicts SAT score from family income is 6.25 points per 1000 dollars, and the correlation between the variables is 0.48. Then the slope of the line that predicts family income from SAT score (in $1000 per point)</p>

<p>A.) 0.037
B.) 0.16
C.) 3.00
D.) 6.25
E.) 13.02</p>

<p>I'm not sure how my teacher did it but she said answer is A...I'm not sure why..
Thanks.</p>

2

<p>I’m not in AP Stats, but I can help with the first one.
Say a standard color TV is 20"-30". (Reasonable size.)
Then think about what the cost would be for such a TV. You’re not going to pay $30 for a 20" TV; same with $3000 for a 20" TV (corresponds to slopes 1.5 and 150, respectively).
Therefore, the slope must be 15</p>

<p>Also, for the second one, <a href=“Classroom Resources - National Council of Teachers of Mathematics”>http://mathforum.org/kb/thread.jspa?forumID=67&threadID=2187171&messageID=7286157&lt;/a&gt;&lt;/p&gt;