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kramer
4 years ago
6

The number of kilograms, y, of a radioactive element that remains after t hours can be modeled by the equation y = 0.23 ( 0.91 )

t . What is the rate of decrease of this radioactive element? A. 9% per hour B. 23% per hour C. 77% per hour D. 91% per hour
Mathematics
1 answer:
Misha Larkins [42]4 years ago
6 0

Answer:

A. 9% per hour

Step-by-step explanation:

we know that

The equation of a exponential decay function is given by

y=a(1-r)^t

where

a is the initial value

r is the rate of decrease

we have

a=0.23\ kg\\1-r=0.91\\r=1-0.91\\r=0.09

Convert to percentage

Multiply by 100

r=0.09(100)=9\%

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Classify the pair of angles, then find the value of x.<br> (PLEASE HELP ME OUT!!)
Leona [35]

Answer:

X = 55°

Step-by-step explanation:

You can tell if a pair of angles, in this case, is 90° if you see the red box in the corner of the angle.

The pair of angles in the picture are complementary angles, which add up to 90°. Therefore, subtract 35 from 90 to find the value of X which is 55°.

Hope this helped! <3

3 0
3 years ago
Using a place value chart which has more tens in it , 10020 or 20010
Luda [366]
If we use the place value chart, 10020 and 20010 will be further dissected based on place values. At first look, 20010 seems to have more tens and that is fact; but this method will show us that it is otherwise so follow the solution below carefully:

Employing PLACE VALUE CHART:

For 20010:
*10000 <--- Ten-thousands place.
*10000 <--- Ten-thousands place.
*10 <--- Tens place.
Add these numbers and you will get: 20010. 20010 has two ten-thousands place and one tens place.

For 10020
*10000 <--- Tens-thousands place.
*10 <--- Tens place.
*10 <--- Tens place.
Add these numbers and you will get: 10020. 10020 has one ten-thousands place and two tens place.

Therefore, there are more tens in 10020 than in 20010.
3 0
3 years ago
Solve the percentage problems. b Find the number if 6% of it is 20% of 6
Fed [463]

Answer:

the number is 20

Step-by-step explanation:

6% of x = 20% of 6

0.06x=0.20*6

0.06x=1.20

x=1.20/0.06

x=20

3 0
3 years ago
Find the gradient of the line joining (-1,9) and (3,5)
givi [52]

\rule{300}{1}\\\dashrightarrow\large\blue\textsf{\textbf{\underline{Given question:-}}}

   <em>Find the gradient of the line joining (-1,9) and (3,5)</em>

<em />\dashrightarrow\large\blue\textsf{\textbf{\underline{Answer and how to solve:-}}}

Use the slope formula:-

\boxed{\frac{y_2-y_1}{x_2-x_1}}

Replace the letters with the numbers:-

\boxed{\frac{5-9}{3-(-1)}}

\circ On simplification,

\boxed{\frac{-4}{3+1}}

\circ On further simplification,

\boxed{\frac{-4}{4}}

\circ\sf{SLOPE=-1}

<h3>Good luck with your studies.</h3>

\rule{300}{1}

5 0
2 years ago
karie builds a skate ramp with 2 metres of wood. she wants the vertical height of the ramp to be 1 metre. what does the angle el
MA_775_DIABLO [31]

9514 1404 393

Answer:

  30°

Step-by-step explanation:

The relationship between triangle sides and angles can be remembered using the mnemonic SOH CAH TOA. Here, we're interested in the relationship involving the hypotenuse and the side opposite the angle:

  Sin = Opposite/Hypotenuse

For a ramp 1 m high and 2 m long, we have ...

  sin(x) = (1 m)/(2 m) = 1/2

  x = arcsin(1/2) = 30°

The elevation angle of the ramp needs to be 30°.

4 0
3 years ago
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