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3 years ago

Drake estimates that he can finish 12 math

Mathematics

2 answers:

lawyer [7]3 years ago

5 0

Answer:

1.5 hours

Step-by-step

If it takes him 45 minutes to do 12 questions it would take him double the time to do 24

zysi [14]3 years ago

3 0

Answer: It will take him 1 hour and 30 minutes, or 1 and a half hours to finish 24 math problems. Another solution could be 1.5 hours!

Step-by-step explanation: We know he can finish 12 math problems in 45 minutes.

To find how many minutes it takes him to complete 24 math problems, simply multiply, 12 x 2 and 45 x 2.

12 x 2 = 24 total math problems.

45 x 2 = 90 Minutes.

90 minutes can also be written as 1 hour and 30 minutes, or 1 and a half hours. That is your answer!

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What is the number that has the same absolute value as 81

LenaWriter [7]

The absolute value of -81 has the same absolute value as that of 81 because they both have the same distance to 0.

4 0

4 years ago

Find the value of x from the equation

Jobisdone [24]

$\dfrac{8^{3x}}{2^{10}}=\dfrac{4^{2x}}{16} \\\dfrac{2^{3(3x)}}{2^{10}}=\dfrac{4^{2x}}{4^2} \\2^{9x-10}=4^{2x-2} \\2^{9x-10}=2^{2(2x-2)} \\2^{9x-10}=2^{4x-4} \\9x-10=4x-4 \\5x-6=0 \\5x=6 \\\boxed{x=\dfrac{6}{5}}$

Hope this helps.

r3t40

3 0

3 years ago

The scores of students on the ACT college entrance exam in a recent year had the normal distribution with mean  =18.6 and stand

Maurinko [17]

Answer:

a) 33% probability that a single student randomly chosen from all those taking the test scores 21 or higher.

b) 0.39% probability that the mean score for 76 students randomly selected from all who took the test nationally is 20.4 or higher

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal probability distribution:

Problems of normally distributed samples are solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the zscore of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.

Central limit theorem:

The Central Limit Theorem estabilishes that, for a random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sample means with size n of at least 30 can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$

In this problem, we have that:

$\mu = 18.6, \sigma = 5.9$

a) What is the probability that a single student randomly chosen from all those taking the test scores 21 or higher?

This is 1 subtracted by the pvalue of Z when X = 21. So

$Z = \frac{X - \mu}{\sigma}$

$Z = \frac{21 - 18.6}{5.4}$

$Z = 0.44$

$Z = 0.44$ has a pvalue of 0.67

1 - 0.67 = 0.33

33% probability that a single student randomly chosen from all those taking the test scores 21 or higher.

b) The average score of the 76 students at Northside High who took the test was x =20.4. What is the probability that the mean score for 76 students randomly selected from all who took the test nationally is 20.4 or higher?

Now we have $n = 76, s = \frac{5.9}{\sqrt{76}} = 0.6768$