How to practice Probability and Statistics

Attempt a question, record the concept and assumptions, then check the available answer. Rework mistakes after revising the relevant concepts. Topic tags can overlap; review the question context.

Questions 1–10 of 14. Imported answers require independent review unless marked reviewed.

Topic practice 14 questionsPage 1 of 2

Question 14

Open question
ESMCQ1 markNeeds review
A box contains 26 cards with all English alphabets from A to Z. The probability of randomly choosing the card with either ‘E’ or ‘S’ from this box is ______.
Your answerChoose one option.

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Question 15

Open question
ESMCQ1 markNeeds review
Which ONE of the following options is the CORRECT formula for Chi-Square (

) test?
Given,

are the observed values,

are the corresponding expected values,

is the mean of observed values,

is the number of observations,

is the mean of

,

,

is the standard deviation of observed values, and

is the standard deviation of expected values

,

.
Your answerChoose one option.

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Question 34

Open question
ESNAT1 markNeeds review
A 6-hour rainfall of 6 cm at a station was found to have a return period of 40 years. The probability that a 6-hour rainfall of this or larger magnitude will occur at least once in 20 successive years at that station is ______ (rounded off to three decimal places).

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Question 24

Open question
ESMSQ1 markNeeds review
Consider the following statements
(i) Environmental pollutant concentration is generally modeled using lognormal distribution. (ii) Environmental pollutant concentration is generally modeled using Poisson distribution. (iii) The weekly rate of exceedance of environmental pollutant concentration with regard to a given standard is generally modeled using lognormal distribution. (iv) The weekly rate of exceedance of environmental pollutant concentration with regards to a given standard is generally modeled using Poisson distribution.
Choose the correct option(s) from the following
Your answerSelect all correct options. You can choose more than one.

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Question 47

Open question
ESNAT2 marksNeeds review
A residential family is considering two cities for relocation. The data related to pollutant exposure and associated health cost per year are given in the following figure.
Diagram for Environmental Science and Engineering question 47

The pollutant exposure is characterized in high, mild and low exposure categories with respective probability values. The difference in expected value of health cost of City 1 with respect to that of City 2 is ____________ lakhs/year. (rounded off to two decimal places).

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Question 7

Open question
GAMCQ2 marksNeeds review
The probability of a boy or a girl being born is 1/2. For a family having only three children, what is the probability of having two girls and one boy?
Your answerChoose one option.

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Question 11

Open question
ESMCQ1 markNeeds review
Ten cards in a pack are numbered as 1, 2, 3, . . .10. The probability of drawing a card with an even number or a number which is a multiple of 5 from the pack is ______.
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Question 36

Open question
ESMCQ2 marksNeeds review
A population (with mean

) follows normal distribution. Ten samples (N) are drawn at random with a mean value of “x” and standard deviation of “S”. Following table provides the confidence limits, C(t) of the cumulative probability function for Student’s t – distribution two-tailed test with degree of freedom D.
Which one of the following expression is correct for testing the null hypothesis H₀:

at 10% significance level?
D
C(t)=0.9
C(t)=0.95
C(t)=0.975
9
1.38
1.83
2.26
10
1.37
1.81
2.23
11
1.36
1.80
2.20
Your answerChoose one option.

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Question 30

Open question
ESNAT1 markNeeds review
A researcher compiled the following information about the performance of a kit in an outbreak
Infection state | Kit response Disease (probability = 0.002) | Positive response (probability = 0.98) No Disease | Positive response (probability = 0.03)
The probability of detecting an infection for a positive result through the kit would be _____________ (rounded off to three decimal places).

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Question 36

Open question
ESMCQ2 marksNeeds review
W₁, W₂, W₃...W₉ represent the holding times of 9 water samples, which follow a normal distribution with mean = 8.33 and standard deviation = 4.472. M represents the sample mean value of holding times, which also has a normal distribution. Assuming Z has a standard normal distribution (mean = 0 and standard deviation = 1), select the correct statement which describes the expression for calculating the value of type 1 error where
null hypothesis (H₀): M > 6
alternate hypothesis (Hₐ): M ≤ 6
Your answerChoose one option.

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