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horsena [70]
3 years ago
11

The half-life of helium-5 is 7.6 × 10-22 seconds, and the half-life of helium-9 is 7 × 10-21 seconds. Approximately how many tim

es greater is the half-life of helium-9 than that of helium-5?
Mathematics
1 answer:
Lorico [155]3 years ago
5 0

Answer:

Step-by-step explanation:

If 10-22 means 10⁻²², you need to use a ^ to indicate the exponent: 10^(-22)

(7×10⁻²¹)/(7.6×10⁻²²) = (7×10⁻²¹)/(0.76×10⁻²¹) = 7/0.76 ≅ 9.2

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How many different 11-letter words (real or imaginary) can be formed from the letters in the word PROBABILITY?
Lostsunrise [7]
<h3>Answer:  9,979,200</h3>

This is one single number. It's just a bit under 10 million

Delete the commas if necessary.

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

Explanation:

If we could tell the repeated letters apart, then there would be

11*10*9*8*7*6*5*4*3*2*1 = 39,916,800

different ways to scramble up the letters.

However, we have 2 copies of b and 2 copies of i

So we have to divide by 2*2 = 4 to correct this overcounting

(39,916,800)/4 = 9,979,200

6 0
3 years ago
g Water use in the summer is normally distributed with a mean of 310.4 million gallons per day and a standard deviation of 40 mi
andreev551 [17]

Answer: The value of b = 0.99

The probability that a day requires more water than is stored in city reservoirs is 0.161.

Step-by-step explanation:

Given : Water use in the summer is normally distributed with

\mu=310.4\text{ million gallons per day}

Standard deviation : \sigma=40 \text{ million gallons per day}

Let x be the combined storage capacity requires by the reservoir on a random day.

Z-score : \dfrac{x-\mu}{\sigma}

z=\dfrac{350-310.4}{40}=0.99

The probability that a day requires more water than is stored in city reservoirs is  :

P(x>350)=P(z>0.99)=1-P(z    

Hence, the probability that a day requires more water than is stored in city reservoirs is 0.161

3 0
4 years ago
Find the value of ln(-7).
const2013 [10]

Answer:

A

Step-by-step explanation:

Here, we want to find the value of ln (-7)

ln is same as Log to base e and mathematically , we have it for positive numbers only

For that of negative numbers, we get undefined results

However, by the use of special mathematical

methods, we have the answer for ln (-7) as;

1.94591015 + 3.14159265 i

As we can see, for the second part, the value for the coefficient of the complex number is pi and thus, we have the correct option as A

4 0
3 years ago
Leonardo put a 600 ring on layaway and putting a 10% down payment to pay $65 a week . How many weeks will it take for him to pay
solmaris [256]
600-10% (10% is 60)
540/65= 8.30
9 weeks
7 0
3 years ago
do you agree that not all quadratic equations can be solved by factoring? justify your answer by giving examples.
Talja [164]
In some cases, there are better solutions than factoring. Consider, for example the quadratic equation x^2+x+1, which is much easier to solve using the quadratic formula than by factoring.
5 0
3 years ago
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