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4 years ago

Does 65-(45-20)equal (65-45)-20? how do you know?

Mathematics

2 answers:

tresset_1 [31]4 years ago

5 0

Answer:

No, the expression 65-(45-20) is not equal to (65-45)-20.

Step-by-step explanation:

Consider the provided expression.

Consider the expression: 65-(45-20)

Solve the above expression as shown.

65-(45-20)

65-(25)

65-25

Now consider the second expression.

(65-45)-20

20-20

Now compare both the result.

40≠0

Hence, the expression 65-(45-20) is not equal to (65-45)-20.

quester [9]4 years ago

4 0

No, it does not. 65-(45-20) is equal to 40, because you subtract 45-20 before because of the parentheses. When you do that, you get 25 then subtract 65-25, then get 40. Then, if you subtract 65-45 first and get 25, then subtract 25-20, you'll get 5.

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I need help! The 20% off sale is a better deal than the $200 rebate or $150 coupon for the $1,500 dining room set. Explain why t

11111nata11111 [884]

Answer:

See explanation

Step-by-step explanation:

The 20% off sale is a better deal because 20% off of $1500 will cost $1200. (See work).

However, the 200 or 150 dollars off will cost $1300-1350. Thus, the better deal for the dining room set is to use the 20% off.

If their budget is $1250, they will be $50 under budget because they would be paying $1200 for the set.

Work:

1500 x 20%

1500 x 0.20 = 300

1500-300= $1200

1500-150= 1350

1500-200= 1300

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4 years ago

Find the positive difference between 16 and -2

snow_tiger [21]

Answer:

Step-by-step explanation:

16-2= 14

Hope this helps!

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3 years ago

The length of a side of a rectangle is 2 units less than a number, and the width is 4 units more than the length. Which of the f

777dan777 [17]

Let's find the expressions for the length and width of the rectangle. The length (which we will call <em>l</em>) is 2 units less than some undefined number, thus we will use the variable <em>x</em>:
l = x - 2

The width is 4 more than this length:
w = l + 4 = (x - 2) + 4 = x + 2

Now, given that we have the length and width and are looking for the area, we need to multiply these expressions together.

One way to write this would simply be (x + 2)(x - 2). If we wanted to find a different way of writing the area, we could use FOIL to find all terms and get x^2 - 4.

6 0

3 years ago

Suppose that 16% of the population of the U.S. is left-handed. If a random sample of 170 people from the U.S. is chosen, approxi

Shalnov [3]

Answer:

0.6064 = 60.64% probability that fewer than 29 are left-handed.

Step-by-step explanation:

Binomial probability distribution

Probability of exactly x sucesses on n repeated trials, with p probability.

Can be approximated to a normal distribution, using the expected value and the standard deviation.

The expected value of the binomial distribution is:

$E(X) = np$

The standard deviation of the binomial distribution is:

$\sqrt{V(X)} = \sqrt{np(1-p)}$

Normal probability distribution

Problems of normally distributed distributions can be 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.

When we are approximating a binomial distribution to a normal one, we have that $\mu = E(X)$ , $\sigma = \sqrt{V(X)}$ .

16% of the population of the U.S. is left-handed.

This means that $p = 0.16$

Sample of 170 people

This means that $n = 170$

Mean and standard deviation:

$\mu = E(X) = np = 170*0.16 = 27.2$

$\sigma = \sqrt{V(X)} = \sqrt{np(1-p)} = \sqrt{170*0.16*0.84} = 4.78$

Probability that fewer than 29 are left-handed.

Using continuity correction, this is P(X < 29 - 0.5) = P(X < 28.5), which is the pvalue of Z when X = 28.5. So

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

$Z = \frac{28.5 - 27.2}{4.78}$

$Z = 0.27$

$Z = 0.27$ has a pvalue of 0.6064

0.6064 = 60.64% probability that fewer than 29 are left-handed.

6 0

3 years ago

Harvey worked 36 hours this week. He earns $28.46 an hour. How much did he earn this week

Snowcat [4.5K]

Answer:

$1,024.56

Step-by-step explanation:

Simple math, So what you would do to find this answer would be taking the amount of money hes earning an hour and times that by how many hours he worked that week. so $28.46 x 36 = $1,024.56

4 0

4 years ago

Read 2 more answers