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3 years ago

Mary bought a desk on sale for 88.40. This price was 74% less than the original price.

Mathematics

1 answer:

kirill115 [55]3 years ago

4 0

Answer: 340

Step-by-step explanation:

100 - 74 = 26%

26% = .26

x * .26 = 88.4

/.26 /.26

x = 340

check

340 * .74 = 251.6

340 - 251.6 = 88.4

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The half-life of caffeine in a healthy adult is 4.8 hours. Jeremiah drinks 18 ounces of caffeinated

statuscvo [17]

We want to see how long will take a healthy adult to reduce the caffeine in his body to a 60%. We will find that the answer is 3.55 hours.

We know that the half-life of caffeine is 4.8 hours, this means that for a given initial quantity of coffee A, after 4.8 hours that quantity reduces to A/2.

So we can define the proportion of coffee that Jeremiah has in his body as:

P(t) = 1*e^{k*t}

Such that:

P(4.8 h) = 0.5 = 1*e^{k*4.8}

Then, if we apply the natural logarithm we get:

Ln(0.5) = Ln(e^{k*4.8})

Ln(0.5) = k*4.8

Ln(0.5)/4.8 = k = -0.144

Then the equation is:

P(t) = 1*e^{-0.144*t}

Now we want to find the time such that the caffeine in his body is the 60% of what he drank that morning, then we must solve:

P(t) = 0.6 = 1*e^{-0.144*t}

Again, we use the natural logarithm:

Ln(0.6) = Ln(e^{-0.144*t})

Ln(0.6) = -0.144*t

Ln(0.6)/-0.144 = t = 3.55

So after 3.55 hours only the 60% of the coffee that he drank that morning will still be in his body.

If you want to learn more, you can read:

brainly.com/question/19599469

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2 years ago

For breakfast, Mrs. Ryan bought a cup of coffee for $2.18 and a pastry for $1.65. How much change will she get back from $5.00?

Tom [10]

Answer:

1.17

Step-by-step explanation:

5-(2.18+1.65)

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2 years ago

What is the hydronium ion (H3O+) concentration in milk if it has a pH of 8.2?

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The hydronium ion is H₃O⁺ and its concentration is equivalent to the H⁺ ion concentration. The H⁺ ion concentration is given by:

pH = -log[H⁺]
[H⁺] = 10^(-8.2)
[H⁺] = 6.31 x 10⁻⁹ mole/dm³

The hydronium ion concentration is 6.31 x 10⁻⁹ mole/dm³

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3 years ago

Three friends are dividing the cost of a kite equally the Kite

Tomtit [17]

Each person will pay $5.25.

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3 years ago

Read 2 more answers

A contractor has submitted bids on three state jobs: an office building, a theater, and a parking garage. State rules do not all

german

Answer:

The following are the answer to this question:

Step-by-step explanation:

In the given question the numeric value is missing which is defined in the attached file please fine it.

Calculating the probability of the distribution for x:

$\to f(x) = 0.19\ for \ x=14\\\\\to f(x) = 0.29 \ for\ x=7\\\\\to f(x) = 0.38\ for \ x=1\\\\\to f(x)=0.14 \ for \ x=0\\$

The formula for calculating the mean value:

$\bold{ E(X)= x \times f(x)}$

$=14 \times 0.19+7 \times 0.29+1 \times 0.38+0\times 0.14\\\\=2.66 + 2.03+0.38+ 0\\\\=5.07$

$\bold{E(X^2) = x^2 \times f(x)}$

$=14^2 \times 0.19+7^2 \times 0.29+1^2 \times 0.38+0^2 \times 0.14 \\\\=196 \times 0.19+ 49 \times 0.29+1 \times 0.38+0 \times 0.14\\\\= 37.24+ 14.21+ 0.38+0 \\\\=51.83$

use formula for calculating the Variance:

$\to \bold{\text{Variance}= E(X^2) -[E(X)]^2}$

$= 51.83 - (5.07)^2\\\\= 51.83 - 25.70\\\\=26.13$

calculating the value of standard deivation:

Standard Deivation (SD) = $\sqrt{Variance}$

$= \sqrt{26.13} \\\\=5.111$

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3 years ago