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Advocard [28]
3 years ago
7

A certain element has a half life of 4.5 billion years. a. You find a rock containing a mixture of the element and lead. You det

ermine that 60​% of the original element​ remains; the other 40​% decayed into lead. How old is the​ rock? b. Analysis of another rock shows that it contains 5​% of its original​ element; the other 95​% decayed into lead. How old is the​ rock?
Mathematics
1 answer:
oee [108]3 years ago
7 0
The rock is about 7
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7nadin3 [17]
It is 255 cm^2

This is a very basic area problem. You should try refreshing on some of your multiplication and addition skills. Try reading patterns, maybe. Also learning geometric proofs is VITAL.
3 0
2 years ago
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Hank has to drain his pool so repairs can be done on a crack on the bottom. The company coming to fix the pool is scheduled to a
Alik [6]

Answer:

The answer to the question: "Will Hank have the pool drained in time?" is:

  • <u>Yes, Hank will have the pool drained in time</u>.

Step-by-step explanation:

To identify the time Hank needs to drain the pool, we can begin with the time Hank has from 8:00 AM to 2:00 PM in minutes:

  • Available time = 6 hours * 60 minutes / 1 hour (we cancel the unit "hour")
  • Available time =  360 minutes

Now we know Hank has 360 minutes to drain the pool, we're gonna calculate the volume of the pool with the given measurements and the next equation:

  • Volume of the pool = Deep * Long * Wide
  • Volume of the pool = 2 m * 10 m * 8 m
  • Volume of the pool = 160 m^3

Since the drain rate is in gallons, we must convert the obtained volume to gallons too, we must know that:

  • 1 m^3 = 264.172 gal

Now, we use a rule of three:

If:

  • 1 m^3 ⇒ 264.172 gal
  • 160 m^3 ⇒ x

And we calculate:

  • x = \frac{160 m^{3}*264.172 gal }{1m^{3} } (We cancel the unit "m^3)
  • x = 42267.52 gal

At last, we must identify how much time take to drain the pool with a volume of 42267.52 gallons if the drain rate is 130 gal/min:

  • Time to drain the pool =\frac{42267.52gal}{130\frac{gal}{min} }(We cancel the unit "gallon")
  • Time to drain the pool = 325.1347692 minutes
  • <u>Time to drain the pool ≅ 326 minutes</u> (I approximate to the next number because I want to assure the pool is drained in that time)

As we know, <u><em>Hank has 360 minutes to drain the pool and how it would be drained in 326 minutes approximately, we know Hank will have the pool drained in time and will have and additional 34 minutes</em></u>.

7 0
2 years ago
Evaluate the following expression for z = -3.<br> -z^6<br> I’m literally so bad at this please help
Kipish [7]

Step-by-step explanation:

{ - z}^{6}  \\ z =  - 3

-  {( - 3)}^{6}  \\  =  - 1 \times ( - 3 \times  - 3 \times  - 3 \times  - 3 \times  - 3 \times  - 3)

= -1 × 729

= -729

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2 years ago
Recently, your parents read in the newspaper that American factory worker jobs have the lowest income ra
Svetllana [295]

Answer:

A. A factory worker does not need a lot of education.

Step-by-step explanation:

The answer is " A " which is a factory worker does not need a lot of education. since most people don't have a PHD degree or anything higher education, it results in a lot of people joining due to the benefit of the factory worker doesn't need a lot of worker which makes it low in demand too.

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2 years ago
O, R and S are points in the same horizontal plane. /OR/ = 20m and /OS/= 32m.The bearing of R and S from O are 030° and 135° res
Viktor [21]
<h3>Answer:  roughly 12.6274 meters</h3>

The more accurate value is 12.6274169979696, though it's not fully exact.

Round this however you need to.

The exact distance 32*sin(45) - 10 meters.

===========================================================

Explanation:

Refer to the diagram below.

I'll use point A in place of point O since the letter 'oh' is very similar looking to the number zero.

Plot point A at the origin (0,0). While at point A, look directly north. Then turn 30 degrees eastward to look at the bearing 030°. Next, move 20 meters along that bearing direction to arrive at point R. Segment AR is 20 meters long.

In the diagram, note how angle RAB is 30 degrees. The side opposite this is BR = m.

We can use the sine ratio to say that

sin(angle) = opposite/hypotenuse

sin(A) = BR/AR

sin(30) = m/20

m = 20*sin(30)

m = 10

-----------------------------------

While still at point A, look directly north and turn 135 degrees clockwise (ie toward the east) and move 32 meters along that bearing. You'll arrive at point S as the diagram shows.

Notice how

angle RAB + angle RAC + angle CAS = 30+60+45 = 135

The remaining angle DAS is 180-135 = 45 degrees.

When focusing on triangle DAS, we can say

sin(A) = DS/AS

sin(45) = n/32

n = 32*sin(45)

n = 22.6274169979696

This value is approximate.

----------------------------------

Subtract the values of m and n

n - m = 32*sin(45) - 10 = exact distance

n - m = 22.6274169979696 - 10

n - m = 12.6274169979696

n - m = 12.6274 = approximate distance

Round it however you need to. I'm choosing to round to four decimal places.

So we see that point S is roughly 12.6274 meters east of point R.

If your teacher wants the exact distance, then stick with 32*sin(45)-10.

8 0
2 years ago
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