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Maurinko [17]
3 years ago
10

A multiple choice test 30 questions, and each question has 5 answer choices (exactly one of which is correct). A student taking

the test guesses randomly on all questions. Using the Normal approximation with continuity correction, determine the approximate probability that the student will get at least as many correct answers as he would expect to get with the random guessing approach.
Mathematics
1 answer:
densk [106]3 years ago
7 0

Answer:

Step-by-step explanation:

Given that a multiple choice test 30 questions, and each question has 5 answer choices (exactly one of which is correct).

When a student taking the test guesses randomly on all questions,p for success in each trial = 1/5 =0.2

As there are two outcomes and each event is independent of the other

X no of correct questions is binomial with n = 30 and p = 0.2

If approximated to normal

mean=np = 15 and Variance = np(1-p) = 4.8

Std dev = 2.191

X is normal (15, 2.191)

His expected value = mean = np

Required prob = P(X>15) = P(X>14.5) using continuity correction

=P(Z>-0.5/2.191) = P(Z>-0.23) =0.5910

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Naily [24]
\bf \qquad \qquad \textit{direct proportional variation}\\\\
\textit{\underline{y} varies directly with \underline{x}}\qquad \qquad  y=kx\impliedby 
\begin{array}{llll}
k=constant\ of\\
\qquad  variation
\end{array}\\\\
-------------------------------\\\\
\begin{array}{llll}
\stackrel{frequency}{f}\textit{ of a vibrating string varies directly}\\
\qquad \qquad \textit{with the square root of the tension }\stackrel{tension}{t}
\end{array}

\bf f=k\sqrt{t}\quad \textit{we also know that }
\begin{cases}
f=300\\
t=8
\end{cases}\implies 300=k\sqrt{8}
\\\\\\
\cfrac{300}{\sqrt{8}}=k\implies \cfrac{300}{\sqrt{2^2\cdot 2}}=k\implies \cfrac{300}{2\sqrt{2}}=k\implies \cfrac{150}{\sqrt{2}}=k
\\\\\\
\textit{and we can \underline{rationalize} it to }\cfrac{150\sqrt{2}}{2}\implies 75\sqrt{2}=k

\bf thus\qquad f=\stackrel{k}{75\sqrt{2}}\sqrt{t}\implies \boxed{f=75\sqrt{2t}}\\\\
-------------------------------\\\\
\textit{now, when t = 72, what is \underline{f}?}\qquad f=75\sqrt{2(72)}
5 0
3 years ago
Read 2 more answers
PLEASE HELP PLEASE!!!
defon

Answer:

We conclude that at x = 0 and x = -1, the value of f(x) = 2ˣ - 1 and g(x) = 1/2x is the same.

Therefore, the solution to f(x) = g(x) is:

  • x = -1
  • x - 0

Step-by-step explanation:

Given the table

x                f(x) = 2ˣ - 1                  g(x) = 1/2x

-2                  -3/4                               -1

-1                    -1/2                               -1/2

0                     0                                   0

1                       1                                   1/2

2                     3                                    1

If we carefully observe, we can determine that

at x = 0, the value of f(x) = 2ˣ - 1 and g(x) = 1/2x is the same.

In other words,

at x = 0

  • f(0) = 0
  • g(0) = 0

Thus,

at x = 0

f(x) = g(x)

Also at x = -1, the value of f(x) = 2ˣ - 1 and g(x) = 1/2x is the same.

In other words,

at x = -1

  • f(-1) = -1/2
  • g(-1) = -1/2

Thus,

at x = -1

f(x) = g(x)

Summary:

Thus, we conclude that at x = 0 and x = -1, the value of f(x) = 2ˣ - 1 and g(x) = 1/2x is the same.

Therefore, the solution to f(x) = g(x) is:

  • x = -1
  • x - 0
6 0
2 years ago
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zepelin [54]
-3/5 to get 10 then divide 10 by 2/3.
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3 years ago
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Answer:

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Step-by-step explanation:

Solve for  a  by simplifying both sides of the equation, then isolating the variable.

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3 years ago
Please help me with this question!
Alina [70]

Answer:

see explanation

Step-by-step explanation:

The sum of the 3 angles in a triangle = 180°, thus

∠1 = 180° - (72 + 57)° = 180° - 129° = 51°

The right angle at the left vertex is composed of 72° and ∠2, thus

∠2 = 90° - 72° = 18°

57° and ∠3 form a straight angle and are supplementary, thus

∠3 = 180° - 57° = 123°

∠4 = 180° - (∠2 + ∠3 ) ← sum of angles in a triangle

∠4 = 180° - (18 + 123)° = 180° - 141° = 39°

4 0
3 years ago
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