Elvie can type 4,200 words in 30 minutes givr the ratio of the time in minutes to the number of words
1 answer:
You might be interested in
Answer:
6 billion years.
Step-by-step explanation:
According to the decay law, the amount of the radioactive substance that decays is proportional to each instant to the amount of substance present. Let be the amount of
and
be the amount of
after
years.
Then, we obtain two differential equations
where and
are proportionality constants and the minus signs denotes decay.
Rearranging terms in the equations gives
Now, the variables are separated, and
appear only on the left, and
appears only on the right, so that we can integrate both sides.
which yields
,
where and
are constants of integration.
By taking exponents, we obtain
Hence,
,
where and
.
Since the amounts of the uranium isotopes were the same initially, we obtain the initial condition
Substituting 0 for in the general solution gives
Similarly, we obtain and
The relation between the decay constant and the half-life is given by
We can use this fact to determine the numeric values of the decay constants and
. Thus,
and
Therefore,
We have that
Hence,
Solving for yields
, which means that the age of the universe is about 6 billion years.
<h2>○=> <u>Solution (6)</u> :</h2>
Ratio of two numbers = 2:3
The larger number = 6
Let the smaller number be x.
Which means :
▪︎<u>Therefore, the smaller number = 4</u>
<h2>○=> <u>Solution (7)</u> :</h2>36 compared to 6 =
Let the number be x.
Which means :
▪︎Therefore, the fractional number is equal to
.
Number of Rose's for 24 red Rose's = 6
This can be written in a ratio as 24:6
Number of roses = 8
Let the number of red roses for these roses be x.
Which means :
▪︎Therefore, 32 red roses are there if there are 8 roses.
<h2>○=> <u>Solution (9)</u> :</h2>Number of children for 2 adults = 7
This can be written in a ratio as 7:2
Number of children in the plaza = 21
Let the number of adults be x.
Which means :
▪︎Therefore, 6 adults were there in the plaza.
<h2>○=> <u>Solution (10)</u> :</h2>Cost of 12 pencils = P60
Cost of 1 pencil :
Thus, the cost of one pencil = P5
Cost of 25 pencils :
= Cost of one pencil × 25
▪︎Therefore, the cost of 25 pencils = P125