# Problems and Exercises

Work in brackets is not to be turned in for grading.
```
Notation:       n       manditory problem

(n)     helper problem

{n}	optional problem

Note: for several of these problems, I have provided you with part of
the answer.  Some correlation coefficients are listed by the problems
and some graphs and more correlation coefficients appear below.  This
is to save you the time of doing this work by hand (YUCK!) or going to
a computer.

with other parts of the homework as well, including making graphs.

P.S. 	Sec 	probs	description
----  	---	-----	-----------

#6 	1.3	82	proportions bounded by Z scores (Table A)
1.3	85	SAT 800s
1.3	98,99	normal quantile plots

2.2	20	heights of couples [r = 0.565]
2.2	23	changes in units [r=r*=0.253]
2.2	24	alcohol vs. tobacco
[r = 0.784, 0.224; which order?]
2.2	27,28	transformations of data and correlation coef.

1.R	106	types of graphs and their uses
1.R	[107]	hospital discharges
1.R	108	histograms and numerical stats
1.R	[110]	driving times

Extra stuff for HW 6:

2-27: Three scatter plots with correlation coefficient given.

- x
20.0+
-
fuel use-
(l/100km)-
-
15.0+
-
-     x                                                   x
-                                                     x
-                                                 x
10.0+         x                                   x	r = -0.172
-                                         x
-             x                   x   x
-                 x           x
-                     x   x
5.0+
------+---------+---------+---------+---------+---------+speed (kph)
25        50        75       100       125       150

-
fuel use-    x
(gallons/-
mile)  -
0.075+
-
-
-
-       x                                        x
0.050+                                             x	r = -0.172
-          x                              x
-                                   x  x
-             x                  x
-                 x        x  x
0.025+                    x  x
-
-
+---------+---------+---------+---------+---------+------speed (mph)
0        20        40        60        80       100

40+                    x
-                       x
fuel use-
(miles/  -                 x        x
gallon) -                             x                     r = -0.045
30+             x
-                                x
-                                   x
-          x                           x
-                                         x
20+                                             x
-       x                                        x
-
-
-    x
10+
-
+---------+---------+---------+---------+---------+------speed (mph)
0        20        40        60        80       100

2-28 stuff:

-
30000+
- x
seed    -
count   - 				r = -0.470
-
20000+
-
-
- x
- x
10000+
- x
- 2
- x
- 2 2
0+   x                2     2        x  x       x
+---------+---------+---------+---------+---------+----
0      1000      2000      3000      4000      5000    seed weight

-
-
10.0+        x
-             x        x             r = -0.929
log of  -              x
seed   -                 x           x
count   -                 x           x
7.5+                              x        x
-                                      x
-                                                 x
-                                       x          x
-                                                  x
5.0+                                                    x
-                                                 x   x
-
-                                                    x
-
+---------+---------+---------+---------+---------+------
-2.0       0.0       2.0       4.0       6.0       8.0   log(seed wght)

```