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3 years ago

Write the following proportion using colons. 7 is to 21 as 3 is to 9.

1 answer:

eduard3 years ago

8 0

This is how proportion is written 7:21=3:9. The colons are sign of division so it can be shown in the terms of fraction as 7/21=3/9 or 1/3=1/3

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Roberto spent 90 minutes doing homework,2/3 hour reading, and 540 seconds making lunch.How many more minutes did he spend doing

poizon [28]

Answer:

first of all convert the hours to minutes

2/3×60=40

convert the seconds to minutes

540÷60=9

add the minutes

40+9=40

so he spent

90-40=50 more minutes in doing his homework.

6 0

3 years ago

PLZZ HELP

avanturin [10]

Answer:

Step-by-step explanation:

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3 years ago

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Super Dave Osborne stands at the bottom of a canyon elevation 256 feet below sea level, he throws a piano up at a velocity of 3

fgiga [73]

Answer:

The piano was in the air for 18.34 seconds.

Step-by-step explanation:

The height of the piano after t seconds is given by the following equation:

$f(t) = -16t^{2} + 320t - 256$

Initially, the piano is below the ground level. At the first root of the equation, it will go into the air, and then some time after that it will fall down again, which is at the second root of the equation.

Roots of a quadratic equation:

Given a second order polynomial expressed by the following equation:

$ax^{2} + bx + c, a\neq0$ .

This polynomial has roots $x_{1}, x_{2}$ such that $ax^{2} + bx + c = a(x - x_{1})*(x - x_{2})$ , given by the following formulas:

$x_{1} = \frac{-b + \sqrt{\bigtriangleup}}{2*a}$

$x_{2} = \frac{-b - \sqrt{\bigtriangleup}}{2*a}$

$\bigtriangleup = b^{2} - 4ac$

In this question:

$f(t) = -16t^{2} + 320t - 256$

$a = -16, b = 320, c = -256$

$\bigtriangleup = (320)^{2} - 4*(-16)*(-256) = 86016$

$t_{1} = \frac{-320 + \sqrt{86016}}{2*(-16)} = 0.8348$

$t_{2} = \frac{-320 - \sqrt{86016}}{2*(-16)} = 19.17$

Subtracting:

19.17 - 0.8348 = 18.34

The piano was in the air for 18.34 seconds.

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3 years ago

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Daniel [21]

The value of a is 2. Hope this helps!

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3 years ago

Kalvin and 4 of his friends want

Pani-rosa [81]

One friend shoud receive 1/4 nuts

1/4 is equivalent to 2/8

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3 years ago

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