I need the answer fast pls

Answer:

The half-life of this radioactive substance is of 8.6 months.

Step-by-step explanation:

Exponential decay of an amount:

The equation that models an amount after t units of time, subject to exponential decay, is given by:

[tex]A(t) = A(0)(1-r)^t[/tex]

In which A(0) is the initial amount and r is the decay rate, as a decimal.

A radioactive substance decays to 30% of its original mass in 15 months.

This means that [tex]A(15) = 0.3A(0)[/tex]. We use this to find 1 - r.

[tex]A(t) = A(0)(1-r)^t[/tex]

[tex]0.3A(0) = A(0)(1-r)^{15}[/tex]

[tex](1-r)^{15} = 0.3[/tex]

[tex]\sqrt[15]{(1-r)^{15}} = \sqrt[15]{0.3}[/tex]

[tex]1 - r = (0.3)^{\frac{1}{15}}[/tex]

[tex]1 - r = 0.9229[/tex]

So

[tex]A(t) = A(0)(0.9229)^t[/tex]

Determine the half-life of this radioactive substance to the nearest tenth.

This is t for which A(t) = 0.5A(0). So

[tex]A(t) = A(0)(0.9229)^t[/tex]

[tex]0.5A(0) = A(0)(0.9229)^t[/tex]

[tex](0.9229)^t = 0.5[/tex]

[tex]\log{(0.9229)^t} = \log{0.5}[/tex]

[tex]t\log{0.9229} = \log{0.5}[/tex]

[tex]t = \frac{\log{0.5}}{\log{0.9229}}[/tex]

[tex]t = 8.6[/tex]

The half-life of this radioactive substance is of 8.6 months.

Answer:

c=29°

Step-by-step explanation:

angle b=97°{ vertically opposite angle}

now,

97°+54°+c=180°{ sum of angle of triangle}

Answer: I'm pretty sure it's 29 degrees.

Step-by-step explanation:

Angle b is directly opposite of 97, and is the same. So b is equal to 97. Every triangle is 180 degrees, so all you have to do is 180 - 54 - 97, which is 29. I hope that helps!!

Answer: I asked my teacher, she said it is c

Step-by-step explanation:

Answer:

yes it's c

have a great day

Answer:

3.$0.9

5.9:3 =3:1

Step-by-step explanation:

3.$5.40÷6=$0.9

Answer:

y = 5.66388 feet, (round that to whatever you need to round to)

Step-by-step explanation:

cos (51) = y/9

cos(51)*9=

y = 5.66388 feet

The probability of incoming freshmen who plan to live on-campus in percentage will be 61.11%. Then the correct option is A.

Its basic premise is that something will almost certainly happen. The percentage of favorable events to the total number of occurrences.

A university administered a survey to all incoming students regarding living arrangements for the upcoming school year.

The results of the survey are displayed in the following two-way relative frequency table.

                                         On-Campus          Off-Campus            Total

Freshmen                               0.44                     0.28                     0.72

Transfer Students                  0.21                      0.07                     0.28

Total                                       0.65                      0.35                        1

Then the probability of incoming freshmen who plan to live on-campus in percentage will be

P = (0.44 / 0.72) x 100

P = 0.6111 x 100

P = 61.11%

The probability of incoming freshmen who plan to live on-campus in percentage will be 61.11%.

Then the correct option is A.

More about the probability link is given below.

https://brainly.com/question/795909

#SPJ5

Answer:

b=69(alternate angle)

b=37(alternate angle)

Answer:

1/5

Step-by-step explanation:

y = 12

12 = 1/5 x 60

12= 12

y = 9

9 = 1/5 x 45

9 = 9

and so on and it always results to one fifth

Answer:

6

Step-by-step explanation:

e = number of elephants

9 times as many monkeys as elephants

m = 9e

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

60 animals all together

e + m = 60

e + 9e = 60

Combine like terms

10e = 60

Divide both sides by 10

e = 6

Answer: There’s technically no answer to this question, unless you specify that the zoo only has monkeys and elephants. If the zoo has more than two types of animal then the ratio doesn’t help because there are unknown variables.

However, if we knew that the zoo only has monkeys and elephants, then:

E = number of elephants

M = number of monkeys

M=9E

M + E = 60

9E+E= 60

10E = 60

E = 6

There are 6 elephants (and 54 monkeys).

Answer:

48

Step-by-step explanation: 1 foot is 12 inches. Since the feet are going up by ones, you can say 1=12, 2=24 (+12), 3=36(+12), 4=48(+12)

Hope this helps

Answer and Step-by-step explanation:

The answer is 48.

Each value of y is a multiple of 12, so for when there is 4 feet, you multiply 12 by 4 to get 48.

For when it is 1 foot, you multiply 12 by 1 to get 12.

For when it is 2 feet, you multiply 12 by 2 to get 24.

For when it is 3 feet, you multiply 12 by 3 to get 36

For when it is 5 feet, you multiply 12 by 5 to get 60.

If you were to continue, the y-values (aka the inches) will always be a multiple of 12.

#teamtrees #PAW (Plant And Water)

Answer:

I think it is b) 70

Step-by-step explanation:

Arrange the numbers in ascending order then find the middle number.

Answer:

70

Step-by-step explanation:

Write down all the data points: 20, 40, 50, 70, 80, 90, 110 and identify which is in the very middle.

Answer:

The answers is " Option B".

Step-by-step explanation:

[tex]CI=\hat{Y}\pm t_{Critical}\times S_{e}[/tex]

Where,

[tex]\hat{Y}=[/tex] predicted value of lead content when traffic flow is 15.

[tex]\to df=n-1=8-1=7[/tex]

 [tex]95\% \ CI\ is\ (463.5, 596.3) \\\\\hat{Y}=\frac{(463.5+596.3)}{2}\\\\[/tex]

     [tex]=\frac{1059.8}{2}\\\\=529.9[/tex]

Calculating thet-critical value[tex]t_{ \{\frac{\alpha}{2},\ df \}}=-2.365[/tex]

The lower predicted value [tex]=529.9-2.365(Se)[/tex]

[tex]463.5=529.9-2.365(Se)\\\\529.9-463.5=2.365(Se)\\\\66.4=2.365(Se)\\\\Se=\frac{66.4}{2.365} \\\\Se=28.076[/tex]

When [tex]99\%[/tex] of CI use as the expected lead content: [tex]\to 529.9\pm t_{0.005,7}\times 28.076 \\\\=(529.9 \pm 3.499 \times 28.076)\\\\=(529.9 \pm 98.238)\\\\=(529.9-98.238, 529.9+98.238)\\\\=(431.662, 628.138)\\\\=(431.6, 628.1)[/tex]

Answer:

78 inches

Step-by-step explanation:

5 hours = 390 inches

1 hour = 390 / 5

1 hour = 78 inches

Therefore the snail travels 78 inches in 1 hour.

Hope this helps!

Answer:

2500

Step-by-step explanation:

Answer:

Step-by-step explanation:Herely/3fcEdSx's li[tex]^{}[/tex]nk to the answer:

bit.[tex]^{}[/tex]

Answer:

see below

Step-by-step explanation:   5 27  6  46

Corrie is 5 inches taller than Jason who is 4 ft. 9 in

Corrie must be 4 ft. 9 in + 5 in. = 5 ft. 2 in       or convert ft to inches and  add

          [4(12) + 9] + 5 = 62     62/12 = 5 ft. 2 in.

Jennifer is 8 in, shorter than Corrie so Corrie is (5 - 8) inches  (-3) inches taller than Jason or 3 in. shorter than Jason

Jennifer is   4 ft. 9 in - 3 in. = 4 ft. 6 in

Answer:

the first two are true and the last two are false

Answer:

A

Step-by-step explanation:

-8 + (-10) = -8 -10

Answer:

105.4º

Step-by-step explanation:

supplementary angles total 180º

180 - 74.6 = 105.4º

Answer:

Champs is 64.8, Footlocker is 64. Footlocker is selling them for cheaper. You would go to Footlocker, as it's .8 off.

Answer:

5 ft

Step-by-step explanation:

30/6 = 5

20/4 = 5

25/x = 5

25/5 = 5

x = 5

Answer:

5 feet

Step-by-step explanation:

the triangles are scaled by the factor of 5

Answer:

68%

Step-by-step explanation:

We observe that the mean of the sample is (61+71)/2 = 66 mph which means the standard deviation of the sample is 5 because 66-5=61 and 66+5=71. The Empirical Rule states that for data observed in a normal distribution, 68% of data will fall within one standard deviation of the mean. Therefore, approximately 68% of vehicles travel between 61 miles per hour and 71 miles per hour.

Answer:70x

Step-by-step explanation: FIND BY OWN

Answer:

(x + 5) and (x -1)

Step-by-step explanation:

Given

The attached graph

Required

The [tex]factors[/tex] of the graph

The x [tex]values[/tex] are where the [tex]curve[/tex] [tex]touches[/tex] the x-axis

The first is at:

[tex]x = -5[/tex]

Add 5 to both sides

[tex]x +5= -5+5[/tex]

[tex]x +5= 0[/tex]

This implies that the first factor is: (x + 5)

The second is at:

[tex]x =1[/tex]

Subtract 1 from both sides

[tex]x - 1 = 1 - 1[/tex]

[tex]x - 1 = 0[/tex]

This implies that the other factor is: (x - 1)

Answer:

A. 8100

Step-by-step explanation:

85 x 86

To estimate, we multiply 85*100, which is the easiest multiplication, as a multiplication by 100 is the same as placing two zeros at the end of the number.

85*100 = 8500

Since 86 < 100, 85*86 < 8500. Thus, the correct estimate is given by option A.

Answer:

2

35

6

Step-by-step explanation:

14/7=2

5*7=35

42/7=6

Answer:

2 gallons and 1/2

Step-by-step explanation:

You just have to subtract 1/2 from 3.

3 - 1/2 = 2 1/2

or

3 - .5 = 2.5

And 2 1/2 is how much more he served.

Answer: 5 times more hot chocolate

Step-by-step explanation:

Answer:

0.1771

Step-by-step explanation:

total number of cards in a deck : 52

number of face card per suite : 3

total number of suites : 4 (hearts, clubs, diamonds, spades)

3 * 4 = total number of face cards

12/52 = 0.23 = probability of drawing a face card

remaining card are non face cards

52-12 = 40

40 non face cards

40/52 = 0.77 = probability of drawing a non face card

probability of drawing a face card followed by a non face card

multiply probabilities together to find combined probability

probability of drawing a face card * probability of drawing a non face card

= 0.23 * 0.77

= 0.1771