BD

Benti Delacruz

University of California, Santa Barbara
Teacher

Biography

I've been teaching high school math for nearly ten years and my passion for it continues to grow and grow. Some of my other hobbies include playing basketball, snowboarding, and traveling.

Education

BS Mathematics
University of California, Santa Barbara

Educator Statistics

Numerade tutor for 4 years
23 Students Helped

Topics Covered

Breaking Limits: Unlock Your Potential with Our Expert Solutions
Exploring the World of Derivatives: A Comprehensive Guide

Benti's Textbook Answer Videos

1

Benti's Quick Ask Videos

06:22
Intro Stats / AP Statistics

The length of human pregnancies from conception to birth varies
according to a distribution that can be modeled by a normal random
variable with mean 268 days and standard
deviation 16 days.
Question 1. What percent of pregnancies
last less than 240 days? Note that
the answer is requested as a percent. Use 2 decimal places in
your answer.
%
Question 2. What percent of pregnancies
last between 240 and 270 days? Note that
the answer is requested as a percent. Use 2 decimal places in
your answer.
%
Question 3. The longest 20% of pregnancies
last at least how many days? (round to the nearest whole day)
days.
07:40
Intro Stats / AP Statistics

A population has a mean of 300 and a standard deviation of 80.
Suppose a sample of size 100 is selected and is used to estimate .
Use z-table.
What is the probability that the sample mean will be within +/-
9 of the population mean (to 4 decimals)? (Round z value in
intermediate calculations to 2 decimal places.)
What is the probability that the sample mean will be within +/-
18 of the population mean (to 4 decimals)? (Round z value in
intermediate calculations to 2 decimal places.)
11:42
Intro Stats / AP Statistics

What price do farmers get for their watermelon crops? In the
third week of July, a random sample of 41 farming regions gave a
sample mean of x bar = $6.88 per 100 pounds of watermelon. Assume
that σ is known to be $1.94 per 100 pounds.
(a) Find a 90% confidence interval for the population mean price
(per 100 pounds) that farmers in this region get for their
watermelon crop (in dollars).
What is the margin of error (in dollars)? (For each answer,
enter a number. Round your answers to two decimal places.)
lower limit $
upper limit $
margin of error $
(b) Find the sample size necessary for a 90% confidence level
with maximal error of estimate E = 0.33 for the mean price per 100
pounds of watermelon. (Enter a number. Round up to the nearest
whole number.) ______________ farming regions
(c) A farm brings 15 tons of watermelon to market. Find a 90%
confidence interval for the population mean cash value of this crop
(in dollars). What is the margin of error (in dollars)? Hint: 1 ton
is 2000 pounds. (For each answer, enter a number. Round your
answers to two decimal places.)
lower limit $
upper limit $
margin of error $
08:21
Intro Stats / AP Statistics

You are interested in finding a 90% confidence interval for the
mean number of visits for physical therapy patients. The data below
show the number of visits for 12 randomly selected physical therapy
patients. Round answers to 3 decimal places where possible.
14
23
10
21
21
23
24
25
24
28
5
22
a. To compute the confidence interval use
a ? z t distribution.
b. With 90% confidence the population mean number of visits
per physical therapy patient is between_______
and______ visits.
c. If many groups of 12 randomly selected physical therapy
patients are studied, then a different confidence interval would be
produced from each group. About_________ percent of these
confidence intervals will contain the true population mean number
of visits per patient and about_________ percent will not
contain the true population mean number of visits per
patient.

10:44
Intro Stats / AP Statistics

07:55
Intro Stats / AP Statistics

Which of the following numbers can be the probability of an event? (answer a, b, or c) a). 1.17 b). -0.56 c). 0.18
2. The set of all possible outcomes of a probability experiment is called __________.
3. How many possible outcomes are there when 4 coins are tossed?
4. What type of probability uses actual experiments to determine probability?
5. If you toss a coin enough times, the number of heads and tails will tend to "even out." This is an example of the law of __________
6. If the probability that it will rain tomorrow is 0.48, what is the probability that it will not rain tomorrow?
7. The sum of the probabilities of all the events in a sample space must equal __________.
8. Two events are independent if they cannot occur at the same time. (answer true or false)
9. Find the probability of getting a number greater than 2 when a single die is tossed.
10. If a pair of dice is tossed:
a). find the probability of getting a sum of 8.
b). find the probability of getting a sum less than 4.
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