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3 years ago

A piano has 88 keys. The ratio of white keys to black keys is 13.9. How many black keys does a piano have?

2 answers:

6 0

Black keys=b
white keys=w
b+w=88|·9
w:b=13/9⇒9w=13b
9b+9w=792
13b+9b=792
22b=792|:22
b=36 keys
w=88-36
w=52 keys

lidiya [134]3 years ago

5 0

Answer:

Step-by-step explanation:

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How do you find the volume in cubic meters

jok3333 [9.3K]

Answer:

The answer is below:

Step-by-step explanation:

To calculate a volume in cubic meters, start by measuring your space. When measuring, find the length, width, and height of the space in meters. Next, multiply the three measurements together to find the volume in cubic meters. It's as easy as that!

You can tell me the length, width,and height and I can do it for you if you don't understand?

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3 years ago

Read 2 more answers

Stock valued at $49.50 decreases in value by 12% each year. How much will the stock be worth in 5 years? Round your answer to th

bearhunter [10]

Answer:

Step-by-step explanation:

f(5)=49.5(0.88)^5

f(5)=$26.12

6 0

3 years ago

when 6 is subtracted from the square of a number, the result is 5 times the number. Find the negative solution.

sveta [45]

When 6 is subtracted from the square of a number, the result is 5 times the number, then the negative solution is -1

<h3><u>Solution:</u></h3>

Given that when 6 is subtracted from the square of a number, the result is 5 times the number

To find: negative solution

Let "a" be the unknown number

Let us analyse the given sentence

square of a number = $a^2$

6 is subtracted from the square of a number = $a^2 - 6$

5 times the number = $5 \times a$

<em><u>So we can frame a equation as:</u></em>

6 is subtracted from the square of a number = 5 times the number

$a^2 - 6 = 5 \times a\\\\a^2 -6 -5a = 0\\\\a^2 -5a -6 = 0$

<em><u>Let us solve the above quadratic equation</u></em>

For a quadratic equation $ax^2 + bx + c = 0$ where $a \neq 0$

$x=\frac{-b \pm \sqrt{b^{2}-4 a c}}{2 a}$

Here in this problem,

$a^2-5 a-6=0 \text { we have } a=1 \text { and } b=-5 \text { and } c=-6$

Substituting the values in above quadratic formula, we get

$\begin{array}{l}{a=\frac{-(-5) \pm \sqrt{(-5)^{2}-4(1)(-6)}}{2 \times 1}} \\\\ {a=\frac{5 \pm \sqrt{25+16}}{2}=\frac{5 \pm \sqrt{49}}{2}} \\\\ {a=\frac{5 \pm 7}{2}}\end{array}$

We have two solutions for "a"

$\begin{array}{l}{a=\frac{5+7}{2} \text { and } a=\frac{5-7}{2}} \\\\ {a=\frac{12}{2} \text { and } a=\frac{-2}{2}}\end{array}$

We have asked negative solution. So a = -1

Thus the negative solution is -1

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3 years ago

HURRICANES A category 3 hurricane reaches speeds up to 20.88 kilometers per hour. The distance from Cuba to Key West is 145 kilo

White raven [17]

Let us assume that the time taken by the category 3 hurricane to travel from Cuba to Key West = X minutes
Speed of the category 3 hurricane is given as 20.88 km/hr
So the category 3 hurricane can travel 20.88 km in 1 hour.
The distance between Cuba and Key West = 145 km
Then
20.88 km is travelled by the category 3 hurricane in = 60 minutes
145 km from Cuba to Key west is travelled by the category 3 hurricane in = X minutes
So,
X = [(145 * 60)/20.88] minutes
= 416.66 minutes
= 17 hours and 36 minutes
Time taken by the category 3 hurricane to reach Key West from Cuba is 17 hours and 36 minutes.

8 0

4 years ago

If it is January then there are 31 days this month write the inverse of the conditional statement

Vera_Pavlovna [14]

January has 31 days so that mean january is friends with christmas.

6 0

3 years ago