If x=36 and Y=4, how many of the following are rational numbers?

Mathematics

1 answer:

Savatey [412]3 years ago

5 0

Answer:

2 of them

Step-by-step explanation:

sqr root xy and the sqr rt x/y

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If a student randomly guesses at 20 multiple-choice questions, find the probability that the student gets exactly four correct.

ad-work [718]

Answer:

Probability = 0.190

Step-by-step explanation:

Given:

Number of questions, 'n' = 20

Each question has four choices.

Let event of choosing correct answer be success and its probability be represented by 'p'.

Therefore, event of choosing wrong answer is failure and its probability be represented by 'q'.

Now, probability of success is choosing one correct answer out of 4 options. So, $p=\frac{1}{4}=0.25$

Now, 'p' and 'q' are complements of each other. Therefore,

$q=1-p=1-0.25=0.75$

Now, we need 4 successes. Therefore, $x=4$

Using Bernoulli's theorem to find 'x' successes from 'n' questions, we get:

$P(x)=_{x}^{n}\textrm{C}p^xq^{n-x}$

Plug in 4 for 'x', 20 for 'n', 0.25 for 'p' and 0.75 for 'q'. Solve.

$P(4)=_{4}^{20}\textrm{C}(0.25)^4(0.75)^{20-4}\\P(4)=_{4}^{20}\textrm{C}(0.25)^4(0.75)^{16}\\P(4)=4845\times (0.25)^4\times (0.65)^{16}\\\\P(4)=0.1896\approx0.190$

Therefore, the probability of getting 4 correct answers out of 20 questions is 0.190.

6 0

3 years ago

A bag contains purple marbles and red marbles, 34 in total. The number of purple marbles is 2 more than 3 times the number of re

Irina-Kira [14]

Answer:

There are 26 purple marbles in the bag.

Step-by-step explanation:

Firstly, you have to make an expression in terms of x where x represent red marbles. Given that the question says purple marbles is 2 more than 3 times the number of red marbles. So the expression is :

Let red marbles = x,

$purple = 2 + 3x$