Which expression means the same as subtract 3 from 7 and then multiply by 4

Answers

Answer 1

Answer:

7-3x4 subtract 3 from 7 means you need to take 3 out of 7 (7-3) then you need to multiply that by 4!

Hope this helped!

Related Questions

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Assume that a lost treasure will be in a certain area of the ocean with probability 0.4, and that a search of that area will find the treasure with probability 0.9 if it is there. What is the conditional probability of the treasure being in the area if the area is searched and no treasure is found?
Write the number 0.0049 in scientific notation.
Assume that, on average, healthy young adult’s dream 90 minutes each night, as inferred from a number of measures, including rapid eye movement (REM) sleep. An investigator wishes to determine whether drinking coffee just before going to sleep affects the amount of dream time. After drinking a standard amount of coffee, dream time is monitored for each of 28 healthy young adults in a random sample. Results show a sample mean, X, of 88 minutes and a sample standard deviation, s, of 9 minutes. (a) Use t to test the null hypothesis at the .05 level of significance (b) If appropriate (because the null hypothesis has been rejected), construct a 95 per-cent confidence interval and interpret this interval
The smaller of two consecutive numbers is x + 3. Find the sum of the two numbers.

A hypothesis regarding the weight of newborn infants at a community hospital is that the mean is 6.6 pounds. A sample of seven infants is randomly selected, and their weights at birth are recorded as:
9.0, 7.3, 6.0, 8.8, 6.8, 8.4, and 6.6 pounds.
If Alpha = 0.05,
1. What is the critical t-value?
2. What is the decision for a statistically significant change in average weights at birth at the 5% level of significance?

Answers

Answer:

1. Critical value t=±2.447

2. The null hypothesis is failed to be rejected.

At a significance level of 0.05, there is not enough evidence to support the claim that the birth weight significantly differs from 6.6 lbs.

Step-by-step explanation:

This is a hypothesis test for the population mean.

The claim is that the birth weight significantly differs from 6.6 lbs.

Then, the null and alternative hypothesis are:

$H_0: \mu=6.6\n\nH_a:\mu\neq 6.6$

The significance level is 0.05.

The sample has a size n=7.

The sample mean is M=7.56.

As the standard deviation of the population is not known, we estimate it with the sample standard deviation, that has a value of s=1.18.

The estimated standard error of the mean is computed using the formula:

$s_M=(s)/(√(n))=(1.18)/(√(7))=0.446$

Then, we can calculate the t-statistic as:

$t=(M-\mu)/(s/√(n))=(7.56-6.6)/(0.446)=(0.96)/(0.446)=2.152$

The degrees of freedom for this sample size are:

$df=n-1=7-1=6$

For a two-tailed test with 5% level of significance and 6 degrees of freedom, the critical value for t is ±2.447.

As the test statistic t=2.152 is under 2.447 and over -2.447, it falls in the acceptance region, so the effect is not significant. The null hypothesis is failed to be rejected.

At a significance level of 0.05, there is not enough evidence to support the claim that the birth weight significantly differs from 6.6 lbs.

Sample mean and standard deviation calculations:

$M=(1)/(n)\sum_(i=1)^n\,x_i\n\n\nM=(1)/(7)(9+7.3+6+. . .+6.6)\n\n\nM=(52.9)/(7)\n\n\nM=7.56\n\n\ns=\sqrt{(1)/(n-1)\sum_(i=1)^n\,(x_i-M)^2}\n\n\ns=\sqrt{(1)/(6)((9-7.56)^2+(7.3-7.56)^2+(6-7.56)^2+. . . +(6.6-7.56)^2)}\n\n\ns=\sqrt{(8.32)/(6)}\n\n\ns=√(1.39)=1.18\n\n\n$

Bob has a concession at Yankee Stadium. He can sell 500 umbrellas at $10 each if it rains. (The umbrellas cost him $5 each.) If it shines, he can sell only 100 umbrellas at $10 each and 1000 sunglasses at $5 each. (The sunglasses cost him $2 each.) He has $2500 to invest in one day, but everything that isn’t sold is trampled by the fans and is a total loss. This is a game against nature. Nature has two strategies: rain and shine. Bob also has two strategies: buy for rain or buy for shine. Find the optimal strategy for Bob assuming that the probability for rain is 50%.

Answers

Answer:

The optimal strategy for Bob is buying for shine (unless he can watch a forecast to know the next day weather).

Step-by-step explanation:

This is a typical problem of hopes to win vs hopes to lose. Let's analyze each of the strategies Bob can adopt in both kinds of weather.

Bob buy for rain:

Bob will buy 500 umbrellas for a cost of $5 each. This is a total cost of $2500.

If it rain, Bob can sell all umbrellas for $10 each. This gives a maximum revenue of $5000. Therefore the maximum profit is $2500. Remember that:

Profit= Revenue - Cost

If it's a sunny day, Bob can only sell 100 umbrellas for $10 each. This gives a maximum revenue of $1000. Therefore the maximum profit is -$1500. That means that in this case, the minimum loss is $1500.

Bob buy for Shine:

Bob will buy 100 umbrellas for a cost of $5 each and 1000 sunglasses for a cost of $2 each. This is a total cost of $2500.

If it's a sunny day, Bob can only sell all umbrellas for $10 each and all sunglasses for $5. This gives a maximum revenue of $6000. Therefore the maximum profit is $3500.

If it rains, Bob can sell only sell all the 100 umbrellas for $10 each but none of the sunglasses. Therefore the maximum profit is $1000. Therefore the maximum profit is -$1500. That means that in this case, the minimum loss is $1500.

In both cases, the worst-case scenario is the same: a loss of $1500.

Nevertheless in the best case scenario buying to shine gives a bigger profit. Therefore if the risk is the same, is better to go for the strategy with better profits.

R(x) = -x+2
s(x)=x²-2
Find the value of r(s(-4)).

Answers

Answer: r(s(-4)) = -12

A student ran out of time on a multiple choice exam and randomly guessed the answers for two problems. Each problem had 5 answer choices - a, b, c, d, e- and only one correct answer. What is the probability that she answered neither of the problems correctly? Do not round your answer. (If necessary, consult a list of formulas.)

Answers

Answer:

there is a 64% chance that the student got both problems wrong

a 32% chance that they got only 1 correct

and a 4% chance that they got both correct

Step-by-step explanation:

There are 25 total possible combinations of answers, with 8 possible combinations where the student would get 1 answer right, and 1 combination where the student would get both answers correct.

$25-9=16$

$(16)/(25) =(x)/(100)$

$(64)/(100)$

$64$ %

$(8)/(25) =(y)/(100)$

$(32)/(100)$

$32$ %

$(1)/(25) =(z)/(100)$

$(4)/(100)$

$4$ %

The use of social networks has grown dramatically all over the world. In a recent sample of 24 American social network users and each was asked for the amount of time spent (in hours) social networking each day. The mean time spent was 3.19 hours with a standard deviation of 0.2903 hours. Find a 99% confidence interval for the true mean amount of time Americans spend social networking each day

Answers

Answer:

The 99% confidence interval for the true mean amount of time Americans spend social networking each day is (3.02 hours, 3.36 hours).

Step-by-step explanation:

The (1 - α)% confidence interval for population mean when the population standard deviation is not known is:

$CI=\bar x\pm t_(\alpha/2, (n-1))* (s)/(√(n))$

The information provided is:

$n=24\n\bar x=3.19\ \text{hours}\ns=0.2903\ \text{hours}$

Confidence level = 99%.

Compute the critical value of t for 99% confidence interval and (n - 1) degrees of freedom as follows:

$t_(\alpha/2, (n-1))=t_(0.01/2, (24-1))=t_(0.005, 23)=2.807$

*Use a t-table.

Compute the 99% confidence interval for the true mean amount of time Americans spend social networking each day as follows:

$CI=\bar x\pm t_(\alpha/2, (n-1))* (s)/(√(n))$

$=3.19\pm 2.807* (0.2903)/(√(24))\n\n=3.19\pm 0.1663\n\n=(3.0237, 3.3563)\n\n\approx (3.02, 3.36)$

Thus, the 99% confidence interval for the true mean amount of time Americans spend social networking each day is (3.02 hours, 3.36 hours).

Order of operation and mathematical con vent ion

Answers

PEMDAS - Parenthesis, exponent, multiply, divide, add, subtract

Final answer:

In mathematics, the order of operations and mathematical conventions are vital to ensure the correct solution of equations. This includes principles like scientific notation for handling large or small numbers, and dimensional analysis for ensuring the validity of equations involving different units of measurement.

Explanation:

The order of operations and mathematical convention are fundamental in accurately solving mathematical equations or expressions. This involves following certain rules, such as the use of scientific notation or the principles of dimensional analysis, to ensure equations and operations are performed correctly and yield valid results.

Take for example scientific notation, used for expressing very large or small numbers. When multiplying two numbers expressed in scientific notation, the process is simplified: you multiply coefficients and add exponents. E.g., (3 × 105) × (2 × 109) = 6 × 1014.

Alternatively, dimensional analysis is a technique used to check the validity of equations involving mathematical operation on quantities. It works on the premise that the units of these quantities have to undergo the same mathematical operations as their numbers. This ensures consistency and coherence of dimensions and units in the expression or equation, preventing impossible situations such as adding length to time.

Learn more about Order of Operations here:

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