Hurry Up! I will give brianliest. PLEASE GIVE EXPLANATION or i wont give brainliest

Mathematics

1 answer:

Anit [1.1K]3 years ago

4 0

Answer:

x = 19

Step-by-step explanation:

Question: find x such that f(x) = 2/3

Given f(x) = (-1/3) x + 7

equate the value of f(x) to be 2/3

hence,

(2/3) = (-1/3)x + 7 (multiply both sides by 3)

(3) (2/3) = (3) (-1/3)x + (3) 7

2 = -x + 21

x = 21 - 2

x = 19

You might be interested in

How do I find the answer to the second question?

dimaraw [331]

The sentence does not make sense because a test can only be 100% not 200

7 0

4 years ago

Suppose you take a 30-question, multiple-choice test, in which each question contains 4 choices: A, B, C, and D. If you randomly

mina [271]

Answer:

(a) The probability you pass the exam is 0.0000501.

(b) The expected number of correct guesses is 7.5.

(c) The standard deviation is 2.372.

Step-by-step explanation:

We are given that you take a 30-question, multiple-choice test, in which each question contains 4 choices: A, B, C, and D. And you randomly guess on all 30 questions.

Since there is an assumption of only 1 correct choice out of 4 which means the above situation can be represented through binomial distribution;

$P(X =x) = \binom{n}{r}\times p^{r}\times (1-p)^{n-r} ; x = 0,1,2,3,......$

where, n = number of trials (samples) taken = 30

r = number of success = at least 60%

p = probbaility of success which in our question is the probability

of a correct answer, i.e; p = $\frac{1}{4}$ = 0.25

Let X = Number of questions that are correct

So, X ~ Binom(n = 30 , p = 0.25)

(a) The probability you pass the exam is given by = P(X $\geq$ 18)

Because 60% of 30 = 18

P(X $\geq$ 18) = P(X = 18) + P(X = 19) +...........+ P(X = 29) + P(X = 30)

= $\binom{30}{18}\times 0.25^{18}\times (1-0.25)^{30-18} + \binom{30}{19}\times 0.25^{19}\times (1-0.25)^{30-19} +.......+ \binom{30}{29}\times 0.25^{29}\times (1-0.25)^{30-29} + \binom{30}{30}\times 0.25^{30}\times (1-0.25)^{30-30}$