There are 28 students in math class. 22 of them passed the test. What percentage passed the test?

1 answer:

8 0

In order to solve this question, we need to set up a proportion. We are trying to solve for a percentage, so the proportion will be 22/28 = x/100, where x is the percentage that 22 is out of 28.

22 / 28 = x / 100
2200 = 28x Cross multiply
x = 78.6% Divide

22 is about 78.6% of 28. Remember that, whenever you need a percentage, just set up a proportion like this one.

Hope this helps!

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A rectangular solid measures 5 cm long by 3 cm wide by 1 cm high. What is the surface-area-to-volume ratio

siniylev [52]

Answer:

Answer below

Step-by-step explanation:

Yo uneed to find the Area/volume

The area of the rectangle is 2×(5cm×1cm)+2(3cm×1cm)+2(5cm×3cm)=10cm+6cm+30cm=36cm^2

Volume=5cm×3cm×1cm=15cm^3

Ratio: 36cm^2/15cm^3=12cm^2/5cm^3

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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.

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