Kirsty Gledhill

Numerade Educator
STEM Student

Biography

Hi there! My name is Kirsty, and I have spent many years studying and tutoring maths and physics. I received my Masters in Mathematics from Durham University in 2020, and am currently studying for my PhD in theoretical physics at Imperial College London. I have been tutoring for over 7 years, working with students of varying ages and abilities.

Education

Kirsty has not yet added their education credentials.

Educator Statistics

Numerade tutor for 4 years
5819 Students Helped

Topics Covered

Integration
Mastering Integration Techniques for Optimal Results
Linear Regression & Correlation: Analyzing Data Relationships

Kirsty's Textbook Answer Videos

01:46
Thomas Calculus

Evaluate the integrals using integration by parts.
$$
\int x \sin \frac{x}{2} d x
$$

Chapter 8: Techniques of Integration
Section 2: Integration by Parts
Kirsty Gledhill
01:13
Business Statistics - For Contemporary Decision Making

Determine the value of the coefficient of correlation, $r$, for the following data.
$$
\begin{array}{|r|r|r|r|r|r|r|r|}
\hline X & 4 & 6 & 7 & 11 & 14 & 17 & 21 \\
\hline Y & 18 & 12 & 13 & 8 & 7 & 7 & 4 \\
\hline
\end{array}
$$

Chapter 12: Simple Regression Analysis and Correlation
Section 1: Correlation
Kirsty Gledhill
1

Kirsty's Quick Ask Videos

12:37
Intro Stats / AP Statistics

Recall: The amount of time (in minutes) X that a student spends on one chapter of homework, with a population mean of 100 minutes and population standard deviation of 100 minutes. For problems #6-10, suppose you take a sample n = 64.
6.) (4 points) Describe x̄ in words, in the context of the problem. State the distribution of x̄.

Kirsty Gledhill
02:53
Intro Stats / AP Statistics

Steve believes that his wife’s cell phone battery does not last
as long as his cell phone battery. On ten different occasions, he
measured the length of time his cell phone battery lasted and
calculated that the mean was 17.7 hours with a standard deviation
of 3.2 hours. He measured the length of time his wife’s cell phone
battery lasted on six different occasions and calculated a mean of
18.8 hours with a standard deviation of 7.5 hours. Assume that the
population variances are the same. Let Population 1 be the battery
life of Steve’s cell phone and Population 2 be the battery life of
his wife’s cell phone. Step 1 of 2 : Construct a 95% confidence
interval for the true difference in mean battery life between
Steve’s cell phone and his wife’s. Round the endpoints of the
interval to one decimal place, if necessary.

Kirsty Gledhill
04:06
Intro Stats / AP Statistics

Suppose that for years the mean of population 1 has been
accepted as the same as the mean of population 2, but that now
population 1 is believed to have a greater mean than population 2.
Letting α = 0.05 and assuming the populations have equal variances
and x is approximately normally distributed, use the following data
to test this belief. Sample 1 Sample 2 43.6 45.3 44.4 49.1 45.2
45.6 40.8 46.5 48.3 45.7 40.1 37.0 42.2 42.3 43.1 38.8 37.0 43.3
41.0 40.1
Sample 1
43.6
45.3
44.4
49.1
45.2
45.6
40.8
46.5
48.3
45.7
Sample 2
40.1
37.0
42.2
42.3
43.1
38.8
37.0
43.3
41.0
40.1
What is the alternative hypothesis?
What is the observed t value?
What is the p-value?
What is the final decision about the null hypothesis and
why?

Kirsty Gledhill
02:32
Intro Stats / AP Statistics

The Harris Poll asked a sample of smokers “Do you believe that
smoking will shorten your life, or not?” Of the 1010 people in the
sample, 848 said “yes.”
a. Harris called residential telephone numbers at random in an
attempt to contact an SRS of smokers. Based
on what you know about national sample surveys, what is likely
to be the biggest weakness in the
survey?
b. We will nonetheless act as if the people interviewed are an SRS
of smokers. Give a 95% confidence
interval of the percent of smokers who agree that smoking will
probably shorten their lives.

Kirsty Gledhill
01:52
Intro Stats / AP Statistics

2. An experiment was run to compare three groups. The sample sizes were 28, 33, and 102, and the corresponding estimated standard deviations were 2.7, 2.6, and 4.8.

a) Is it reasonable to use the assumption of equal standard deviations when we analyze these data? Give a reason for your answer.
b) ANOVA assumes that the standard deviation/variance is the same for all the groups. If this common standard deviation is denoted by σ, give a pooled estimate for it.
c) Why do you think the value in part b) is very close to the standard deviation of group 3 (one with 102 observations)?

Kirsty Gledhill
04:26
Intro Stats / AP Statistics

You will need to use the following information for the next few questions. It will be repeated for each question. There is a population of five people: Amy, Brianna, Carlos, Darius, & Eirik. [Note: this is a population, not a sample.] They are asked how many hours they studied last month. Amy studied 10 hours, Brianna studied 22 hours, Carlos studied 18 hours, Darius studied 26 hours, and Eirik studied 4 hours. We are too lazy to poll the entire population, so we take a sample of two (with replacement and order matters).

What is the probability that the mean of the sampling distribution equals the mean of the population?
What is the probability that your error (the distance between what you want to know and your estimate of what you want to know) is two hours or less?
If we increased the sample size to four (instead of two), what would the standard error of the sampling distribution of the mean equal?

Kirsty Gledhill
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