Raymond Matshanda

University of California, Santa Cruz
Tutor

Biography

Mathematics Tutor, Research Specialist, Engineer, Virtual Assistant

Excellent written and communication skills,
Proficiency in using Business Application Software
Mathematics teacher for 14 years (junior and senior high school, university)
Reasearch Specialist
Machine Learning
Data Science
MS in Applied Mathematical Sciences graduate with published research on Statistics

Education

BS Mathematics
University of California, Santa Cruz

Educator Statistics

Numerade tutor for 5 years
607 Students Helped

Topics Covered

Unlocking the Power of Functions: Boost Your Programming Skills
Mastering Integration Techniques for Optimal Results
Mastering Partial Derivatives: Essential Techniques and Tips
Exploring the Functions of Multiple Variables
Unlocking Insights with Descriptive Statistics: A Comprehensive Guide
Exploring Probability Topics: From Basics to Advanced Strategies
Linear Regression & Correlation: Analyzing Data Relationships
Understanding Continuous Random Variables: Key Concepts
Hypothesis Testing with One Sample: A Comprehensive Guide
Unlocking Insights with Non-Parametric Statistics | Boost Your Analysis
Mastering Analysis of Variance: Techniques for Accurate Results
Maximizing Accuracy with Effective Sampling and Data Analysis
Unlocking the Power of Confidence Intervals: A Comprehensive Guide

Raymond's Textbook Answer Videos

03:42
Probability and Statistics for Engineers and Scientists

The following measurements were recorded for the drying time, in hours, of a certain brand of latex paint.
$$
\begin{array}{lllll}
3.4 & 2.5 & 4.8 & 2.9 & 3.6 \\
2.8 & 3.3 & 5.6 & 3.7 & 2.8 \\
4.4 & 4.0 & 5.2 & 3.0 & 4.8
\end{array}
$$
Assume that the measurements are a simple random sample.
(a) What is the sample size for the above sample?
(b) Calculate the sample mean for this data.
(c) Calculate the sample median.
(d) Plot the data by way of a dot plot.
(e) Compute the $20 \%$ trimmed mean for the above data set.

Chapter 1: Introduction to Statistics and Data Analysis
Section 4: Measures of Location: The Sample Mean and Median
Raymond Matshanda
05:36
Probability and Statistics for Engineers and Scientists

According to the journal Chemical Engineering, an important property of a fiber is its water absorbency. A random sample of 20 pieces of cotton fiber is taken and the absorbency on each piece was measured. The following are the absorbency values:
$$
\begin{array}{rrrrrrrr}
18.71 & 21.41 & 20.72 & 21.81 & 19.29 & 22.43 & 20.17 \\
23.71 & 19.44 & 20.50 & 18.92 & 20.33 & 23.00 & 22.85 \\
19.25 & 21.77 & 22.11 & 19.77 & 18.04 & 21.12 &
\end{array}
$$
(a) Calculate the sample mean and median for the above sample values.
(b) Compute the $10 \%$ trimmed mean.
(c) Do a dot plot of the absorbency data.

Chapter 1: Introduction to Statistics and Data Analysis
Section 4: Measures of Location: The Sample Mean and Median
Raymond Matshanda
06:33
Probability and Statistics for Engineers and Scientists

In a study conducted by the Department of Mechanical Engineering at Virginia Tech, the steel rods supplied by two different companies were compared. Ten sample springs were made out of the steel rods supplied by each company and a measure of flexibility was recorded for each. The data are as follows:
$$
\begin{array}{rrrrrr}
\text { Company A: } & 9.3 & 8.8 & 6.8 & 8.7 & 8.5 \\
& 6.7 & 8.0 & 6.5 & 9.2 & 7.0 \\
\text { Company B: } & 11.0 & 9.8 & 9.9 & 10.2 & 10.1 \\
& 9.7 & 11.0 & 11.1 & 10.2 & 9.6
\end{array}
$$
(a) Calculate the sample mean and median for the data for the two companies.
(b) Plot the data for the two companies on the same line and give your impression.

Chapter 1: Introduction to Statistics and Data Analysis
Section 4: Measures of Location: The Sample Mean and Median
Raymond Matshanda
10:39
Probability and Statistics for Engineers and Scientists

Twenty adult males between the ages of 30 and 40 were involved in a study to evaluate the effect of a specific health regimen involving diet and exercise on the blood cholesterol. Ten were randomly selected to be a control group and ten others were assigned to take part in the regimen as the treatment group for a period of 6 months. The following data show the reduction in cholesterol experienced for the time period for the 20 subjects:
$$
\begin{array}{lrrrrr}
\text { Control group: } & 7 & 3 & -4 & 14 & 2 \\
& 5 & 22 & -7 & 9 & 5 \\
\text { Treatment group: } & -6 & 5 & 9 & 4 & 4 \\
& 12 & 37 & 5 & 3 & 3
\end{array}
$$
(a) Do a dot plot of the data for both groups on the same graph.
(b) Compute the mean, median, and $10 \%$ trimmed means for both groups.
(c) Explain why the difference in the mean suggests one conclusion about the effect of the regimen, while the difference in medians or trimmed means suggests a different conclusion.

Chapter 1: Introduction to Statistics and Data Analysis
Section 4: Measures of Location: The Sample Mean and Median
Raymond Matshanda
01:58
Probability and Statistics for Engineers and Scientists

Find the mean of the random variable $T$ representing the total of the three coins of Exercise 3.25 on page 89 .

Chapter 4: Mathematical Expectation
Section 1: Mean of a Random Variable
Raymond Matshanda
1 2 3 4 5 ... 80

Raymond's Quick Ask Videos

04:17
Intro Stats / AP Statistics

Consider the following population of quiz scores (18, 33, 7, 29,
24, 12, 6, 27, 15, 23)
A. State the mode, if one exists
B. Apply the empirical rule at the 95% level.
C. What percentage of these quiz scores actually lie within the
interval found in part b?

Raymond Matshanda
05:12
Intro Stats / AP Statistics

a) Vehicle speeds on highway I-5 (9 vehicles): 47, 56, 94, 76, 75, 56, 84, 72, 89
b) Sodium grams in canned soup (8 varieties): 4.57, 4.29, 3.62, 3.67, 4.13, 3.74, 4.85, 4.28
c) Campus health center visits (12 students): 0, 5, 6, 17, 0, 2, 0, 1, 2, 0, 5, 3

For each data set, find the median, midrange, and geometric mean.

Raymond Matshanda
01:36
Intro Stats / AP Statistics

The mean years of schooling in the United States is 13.4 years.
Let's test if the mean years of schooling in a sample of 48 adults
is significantly different than 13.4 years. Your sample mean is
13.8 years and your sample standard deviation is 2.01 years.
Compute the appropriate Cohen's d to measure effect size. What is
d, rounded to 2 decimal places?

Raymond Matshanda
05:32
Intro Stats / AP Statistics

100 people were asked how many cups of coffee they consume, data
below:
0 cups of coffee: 10/100 people
1 cup of coffee: 20/100
2 cups of coffee: 34/100
3 cups of coffee: 15/100
4 cups of coffee: 5/100
5 cups of coffee: 6/100
6 cups of coffee: 10/100
a) Find the mode of the data.
b) Find the 5 number summary and make a box and whisker
chart.
c) In your opinion which measure of center (mean, median, or
mode) best captures the average number of cups of coffee consumed
at home? Explain why.

Raymond Matshanda
05:22
Calculus 1 / AB

Draw a Markov chain with at least 4 states, and then write the
matching transition matrix. Be sure to explain what the situation
is that your Markov chain is modeling. What do each of the states
mean? Why do the probabilities make sense?

Raymond Matshanda
03:10
Intro Stats / AP Statistics

A random sample of 225 statistical tutorials was selected for the past few years, and the number of students absent was recorded. The mean value was 11.6 with a sample standard deviation of 4.1. Construct a 90% confidence interval for the mean number of absences.

Raymond Matshanda
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