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3 years ago

Bismuth-212 has a half-life of 60.5 minutes. Find the amount of bismuth-212 left from a 100-gram sample after 242 minutes

1 answer:

5 0

Notice that 242 = 4*60.5. This means after 242 minutes, the sample decays to $\dfrac1{2^4}=\dfrac1{16}$ of its original amount. So you end up with

$\dfrac{100\,\mathrm g}{16}=\boxed{6.25\,\mathrm g}$

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A sequence is generated by the formula ax = 3x + 4. What is the value of the seventh term?

lyudmila [28]

Answer:

Explanation:

We are given the sequence formula expression;

ax = 3x + 4

You are to get the 7th term. This is gotten by substituting x = 7 into the expression as shown;

a7 = 3(7) + 4

a7 = 21 + 4

a7 = 25

Hence the seventh term of the sequence is 25

5 0

1 year ago

• a helicopter hovering at 10 m above the ground is shining a spotlight at a person 30 m away1 . if the person is 2 m tall how l

pshichka [43]

As shown in the figure

Height of helicopter above the ground=30 m

Distance from the base to the point where the person is standing=30 m

height of the person=2 m

Now the person cast the shadow of length x m.

Triangle ABC and triangle EDC are similar.

∵ ∠B= ∠D=90°

∠C is common.

So by AA similarity ΔABC and ΔEDC are similar.

As we know when triangles are similar their sides are proportional.

AB/AD =BC/DC

Let DC=x meter

⇒ $\frac{10}{x}=\frac{30+x}{x}$

⇒5=\frac{30+x}{x}[/tex]

⇒5x=30+x

⇒4x = 30

⇒ x=30/4

⇒ x=7.5 meter

So length of shadow=7.5 meter

2. volume of a sphere of radius r is v (r) = $\frac{4}{3}π r^{3}$

$\frac{\mathrm{d} }{\mathrm{d} r}V$ =4/3π×3 $r^2$

=4π $r^2$

surface area of a sphere of radius r is 4π $r^2$

b) Ratio of derivative of volume of sphere to surface area of sphere= $\frac{4\pi r^2}{4\pi r^2}$

=1 [ incomplete question but you have written few words ]

4 0

3 years ago

Lilian says that 25% of a number will always be less than 75% of any other number. Complete one inequality to support Lillian's

rjkz [21]

She is incorrect cause if we take the number 20 and take 25% of it it equals 5 so now 20 is only 15. They if we take 75% away from 20 is equals 15 so then we only have 5 from 20 left. Therefore she’s incorrect because 75% leaves 5/20 and 25% leaves 15/20. Hope that makes sense.

6 0

3 years ago

What’s the length of the missing leg?!

posledela

So the right answer is 12 m.

Look at the attached picture

Hope it will help you..

-Pragya~~

8 0

3 years ago

Someone help me with this question for 15 pts and a brainliest

Rudik [331]

Answer: 46

Step-by-step explanation:

you just do 30 + 16

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3 years ago