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3 years ago

An old cell phone battery would last for 16 hours. The new battery lasts 25% longer. How long will the new battery last?

Mathematics

1 answer:

Aliun [14]3 years ago

7 0

Answer:

20 hours

Step-by-step explanation:

To find the answer, you first should find out how long is 25% of the original battery life, 16 hours. To find this, you can divide 16 by 4, or multiply 16 by 0.25. Either works.

16/4=4.

So the new battery lasts 4 hours more than the old battery. Then, add this to the original length to find how long the new battery will last in total.

16+4=20

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Element X is a radioactive isotope such that its mass decreases by 59% every day. If an experiment starts out with 390 grams of

miss Akunina [59]

Answer:

The function that represents the mass of the sample after t days is $A(t) = 390(0.41)^t$ .

The percentage rate of change per hour is of -2.46%.

Step-by-step explanation:

Exponential amount of decay:

The exponential amount of decay for an amount of a substance after t days is given by:

$A(t) = A(0)(1-r)^t$

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

Element X is a radioactive isotope such that its mass decreases by 59% every day. The experiments starts out with 390 grams of Element X.

This means, respectively, that $r = 0.59, A(0) = 390$

$A(t) = A(0)(1-r)^t$

$A(t) = 390(1-0.59)^t$

$A(t) = 390(0.41)^t$

The function that represents the mass of the sample after t days is $A(t) = 390(0.41)^t$ .

Hourly rate of change:

Decreases by 59% every day, which means that for 24 hours, the rate of change is of -59%. So

-59%/24 = -2.46%

The percentage rate of change per hour is of -2.46%.

5 0

3 years ago

If x = y, y = 2 then 3x =

kenny6666 [7]

Answer:

x=y

y=x

y=2

x=2

(3)(2)

3 times 2 is 6

Step-by-step explanation:

6 0

3 years ago

Urgent help, please!.....

pishuonlain [190]

To solve this problem, we want to get all of the possible options into the same form, so that it is easier to compare them. Personally, I prefer comparing in decimals, so that is how I am going to solve this problem.

13/4 - To turn this improper fraction into its decimal equivalent, it is easier to first turn it into a mixed number by dividing the numerator by the denominator.

13/4 = 3 1/4

Because we know that 1/4 = 0.25, we now know that 3 1/4 = 3.25

Therefore, 13/4 = 3.25

3 1/2 - This is similar to the end of the process above. We know that 1/2 = 0.5, so we know that 3 1/2 = 3.5

3 1/2 = 3.5

3.15 is already in its decimal form, so we can leave that be for now.

√9 - To simplify this, we must figure out what number multiplied by itself equals 9. If we start with 2 (2*2 = 4), so that is too small. Next maybe we try 4 (4 * 4 = 16), so that is too large. Now we know we need a number in between 2 and 4, so maybe we try 3. 3 * 3 = 9, so we can conclude that √9 = 3.

√9 =3

If we take all of our decimal equivalents, we have 3.25, 3.5, 3.15, and 3.

Because all of these values have the same whole number value of 3, we need to compare the decimals to find out what order they belong in.

Our final order is (from smallest to largest): 3, 3.15, 3.25, 3.5

But, we need to substitute in the equivalent values we were given for these decimals originally to finish the problem.

This makes your final answer: √9, 3.15, 13/4, 3 1/2

Hope this helps!

4 0

4 years ago

Read 2 more answers

Jasmine jumps form 18 ft above sea level to 6 ft below sea level. Kim jumps for, 14 ft above sea level to 5 ft above sea level.

DENIUS [597]