So if the ratio is 2:3, then the younger child would represent the 2. so it would be 2:3 is 4:x. Thereby, the answer would be 6, because of proportions. To check, simplify 4:6, and you would get 2:3.
The time taken for the element X to decay from 560 grams to 150 grams is 24.7 mins
<h3>How to determine the number of half-lives </h3>
- Original amount (N₀) = 560 g
- Amount remaining (N) = 150 g
- Number of half-lives (n) =?
2ⁿ = N₀ / N
2ⁿ = 560 / 150
2ⁿ = 3.73
Take the log of both side
Log 2ⁿ = Log 3.73
nLog 2 = Log 3.73
Divide both side by Log 2
n = Log 3.73 / Log 2
n = 1.9
<h3>How to determine the time </h3>
- Number of half-lives (n) = 1.9
- Half-life (t½) = 13 mins
t = n × t½
t = 1.9 × 13
t = 24.7 mins
Learn more about half life:
brainly.com/question/26374513
Answer: (b) Provide hints on what the teacher thinks is important
Explanation: Clearly, the teacher selects what to ask in the tests, and it is plausible to think that (s)he will select problems that they deem important.
The teacher will know that students look at past tests, and so they will tend to change the wording and values in the tests to prevent plagiarism, so (a) is not the right choice.
Let us assume the two numbers to be "x" and "y".
Then
xy = - 24
x = - (24/y)
And
x + y = 2
Putting the value of x from the first equation in the second equation, we get
x + y = 2
- (24/y) + y = 2
- 24 + y^2 = 2y
y^2 - 2y - 24 = 0
y^2 - 6y + 4y - 24 = 0
y(y - 6) + 4(y - 6) = 0
(y - 6) (y + 4) = 0
When
y - 6 = 0
y = 6
Then
x + y = 2
x + 6 = 2
x = 2 - 6
= -4
And when
y + 4 = 0
y = -4
Then
x + y = 2
x - 4 = 2
x = 2 + 4
= 6
So the two unknown numbers are -4 and 6.
Here is your answer to your question.
