Let's say that for one of the two questions you can narrow the answer choices down to three. Now your chance of getting that question right by guessing is about .33. What is the new expected value for the number of questions you'd get right by guessing? What are the new variance and standard deviation of this random variable? Drawing another tree diagram and making another probability distribution table may help you answer this question.
Let's say that for one of the two questions you can narrow the answer choices down to three. Now your chance of getting that question right by guessing is about .33. What is the new expected value for the number of questions you'd get right by guessing? What are the new variance and standard deviation of this random variable? Drawing another tree diagram and making another probability distribution table may help you answer this question.
Chapter8: Sequences, Series,and Probability
Section8.7: Probability
Problem 4ECP: Show that the probability of drawing a club at random from a standard deck of 52 playing cards is...
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Let's say that for one of the two questions you can narrow the answer choices down to three. Now your chance of getting that question right by guessing is about .33.
What is the new
What are the new variance and standard deviation of this random variable?
Drawing another tree diagram and making another probability distribution table may help you answer this question.
(The pictures below are already answer , they are needed to anwer this question)(also zoom in since I could only share 2 pictures)
Transcribed Image Text:1. You're taking a multiple-choice exam and you don't know the answers to two of the questions.
Each question has five choices, so the probability of getting a question right by guessing is
20. Draw a tree diagram showing the probabilities of getting none, one, or both questions
right by guessing.
P(x-x) = (2) P²Y/-pn-x
X is rendons var jave donets no.
of questions quis sed righ
non quessed Right
[P(x=0) = ( 3 ) x (0₂2)x(1-0,2)/12-07
(0.8)2
Ix0.64
One guessed right
P(x-1)=(?)x(0.2) ¹x (1-6.2) (2-1)
*72-17 (0.2) ¹x (0.8)
= 2x0.2x0.8 = 0.32
One guessed right is 0.32
botiguessed right
han quesses right 0.64
P(x-2)=(x(0.27²x(1-0.2) (2-2)
=(D) X (0.2) ² X (0.8)°
_=1 *0.04 = 0.04
Both guessed right is 0.04
-0.645
(None
getting none right by guessing
0.36
One
-0.04
Both
Transcribed Image Text:2. Using the tree diagram you just constructed and make a table showing the probability
distribution of getting zero, one, or both questions right by guessing.
Probability of choosing a
GerreaSUNEY PLO) .20
The leck ability of choosing
X. Denates the number of corredh
LONGUES XTO,1,3
eine C
10.04
P(x)=0.200.80
020
0:00 0.20 Ⓒ
©
2.00
PCK=0,20x0.80
لعليم -
P(x=270020×6-20-
+(x)=0.80X 0.60
+0.69+
The probability value corresponding
to one question is right by guesting thi
P(x=1)=0-1640.16
for getting bal, and both right
X
0
2
PGTA) 0.64 0.32 0.04
3. Find the expected value of the number of questions you'd get right by guessing.
What are the variance and standard deviation?
finding the expected welve
E(x) = ExP(x^x)
0x0.64+1x0.32 + 2x0.04.
0+0.32+0.08
1-0.40
expected value of
probability distribution is 0.40
finding the variance
E (x²) xP(x+x)
~0²³ 0.64 + 1²x 0.32+2 x 0.04
V
Finding Standard
Devention
50 = √Var (X)
=√0.32
= 0.545485
€0.5657
SD of probability
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