All categories

3 years ago

The half-life of chromium−51 is 27.8 days. How much of a 7.6−oz sample of chromium−51 will remain after 139 days?

1 answer:

6 0

Ending Amount = Beginning Amount / 2^n
where "n" is the number of half-lives
n = 139 / 27.8 = 5 half-lives
Ending Amount = 7.6 oz / 2^5
Ending Amount = 7.6 oz / 32
Ending Amount = .2375 ounces

Source:
http://www.1728.org/halflife.htm

You might be interested in

(-----×1/4)÷6×3/9 I need the step to this problem so that I explain to my grandson how he he gets the answer

lesya692 [45]

Answer:

-----×1/72

Step-by-step explanation:

The order of operations says do these operations in order left to right. Please note that ÷ means the same as / unless you define it otherwise in your problem statement.

If you intend the ÷ symbol to be used to indicate everything to its left is divided by everything to its right, it is appropriate to use parentheses for that grouping, as in ...

(-----×1/4)÷(6×3/9) = (-----×1/4)÷2 = -----×1/8

_____

Here, we're going to evaluate what you have written according to the usual rules as described above.

(-----×1/4)÷6×3/9 = -----×1/24×3/9 = -----×(3/24)/9

= -----×1/8/9

= -----×1/72

_____

Comment on the arithmetic

Fractions are multiplied and divided in the usual way:

a/b×c = (a×c)/b

a/b/c = (a/b) × (1/c) = a/(b×c)

___

Comment on fractions and parentheses

Please note that parentheses are required on any numerator or denominator that consists of anything other than a single number or variable. (The exception is the case where the numerator is a product, because a·b/c = (a·b)/c with or without the parentheses.)

6 0

3 years ago

Which system is equivalent to the system shown and could be used to solve the system of equations correctly using the eliminatio

Bumek [7]

Answer:

The solution is (2, -2)

Step-by-step explanation:

In order to solve this, multiply the second equation by -5 and then add through.

5x - 4y = 18

-5x - 15y = 20

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

-19y = 38

y = -2

Now that we have the value of y, we can solve for x.

x + 3y = -4

x + 3(-2) = -4

x - 6 = -4

x = 2

5 0

3 years ago

Find the area of the kite. Hint: The brackets indicates the full length of a segment

xxMikexx [17]

Answer: 54 ft²

Step-by-step explanation:

Area of a kite is calculated by the formula:

= (Length * Height) / 2

Length = 6 + 6 = 12 ft

Height = 9 ft

Area = (12 * 9) / 2

= 108 / 2

= 54 ft²

3 0

2 years ago

SHORT ANSWER Graph and label point W(4, –1) on the coordinate plane.

Lunna [17]

Answer:

Step-by-step explanation:

a coordinate point is (x, y) so for point W (4, -1), 4 is the x-coordinate and -1 is the y-coordinate.

Start at the origin (O). Go 4 units to the right (along the x-axis in a positive direction) and then 1 unit down (in the y plane in a negative direction).

4 0

1 year ago

What is the sales tax

hichkok12 [17]

Answer:

Before Tax Price: $110.00

Sale Tax: 6.10% or $6.71

After Tax Price: ($116.71)

Step-by-step explanation:

6 0

2 years ago