Solutions to Homework Assignment #1
Statistics 220, Fall 2005
Due September 7, 2005
1.10
a
The stem-and-leaf plot should look something like this.
5|9
6|33588
7|00234677889
8|127
9|077
10|7
11|368
What constitutes large or small variation usually depends
36-220 Fall 2016
Homework Assignment 2
Due: Wednesday, October 5, at the beginning of lecture.
Point distribution:
Problem:
Pts:
1
15
2
5
3
15
4
5
5
15
6
5
7
10
8
10
9
10
TOTAL
90
Instructions:
Write up your solutions on separate paper, with your name on
Solutions: Assignment 10
November 23, 2005
12.4
0
20
40
60
80
100
120
140
a.
x
y
Figure 1: boxplot for 12.4
There are a couple of interesting features. First, we see that both x and
y have outliers. 2 each. Also, y looks skewed.
b. The scatterplot shows a
Solutions to Homework #9, 36-220
Due 16 November 2005
8.54
We are supposed to test whether the true average percentage of organic matter
in such soil is something other than 3%. So our null hypothesis H0 is that = 3.
We need a two-sided test, since we wan
36-220 Engineering Stats, Fall 2005
Homework 8 Solutions
Due: November 9, 2005
Exercise 8.4
We consider these two hypothesis tests:
H0 :
H1 :
Test 1
=5
>5
Test 2
=5
<5
A desirable hypothesis test keeps the occurrences of type I error (false positives) and
Solutions: Assignment 7
November 1, 2005
N.D. 1
a.
X bin(n, p)
E [X ] = np
V (X ) = np(1 p)
E [] = E [
p
X
1
] = E [X ]
n
n
1
[np] = p
n
Bias = (E [] p) = p p = 0
p
=
b.
X
1
1
) = 2 V (X ) = 2 (np(1 p)
n
n
n
p(1 p)
=
n
V () = V (
p
c.
S.E () =
p
V () =
p
Solutions to Homework #6, 36-220
Due 12 October 2005
Non-Devore Problem
The rule for variances which says Var (X + Y ) = Var (X ) + Var (Y ) only applies
if X and Y are uncorrelated random variables, for instance, if X and Y are
independent. But here the
36-220 Engineering Stats, Fall 2005
Homework 5 Solutions
Due: October 5, 2005
Non-Devore Exercise
Let T be an exponential random variable that represents the time until a radioactive atom decays
and be the rate of decay.
a) We formulate the following prob
Solutions to Homework Assignment #3
Statistics 220, Fall 2005
Due September 21, 2005
2.52
Let A1 = pump #1 fails, and A2 = pump #2 fails. Because the pumps are
identical, we can assume that Pr (A1 ) = Pr (A2 ) = q . The problem requires us
to nd q .
The e
Solutions to Homework Assignment #2
Statistics 220, Fall 2005
Due September 14, 2005
The following formula is true for any two events A and B , and is useful in
several problems:
P (A B ) = P (A) + P (B ) P (A B )
It follows from the formula for unions, P
36-220 Fall 2016
Homework Assignment 1
Due: Wednesday, September 21, at the beginning of lecture.
Point distribution:
Problem:
Pts:
1
10
2
15
3
20
4
10
5
20
6
25
7
15
8
5
9
10
TOTAL
130
Instructions:
Write up your solutions on separate paper, with your n