Answer:
There are 40 students in the class.
Step-by-step explanation:
We are given the following in the question:
Percentage of class that failed = 15%
Percentage of class that made mistakes but did not fail = 25%
Number of students that got perfect score = 24
Percentage of students that got perfect score =
Let x be the total number of students in the class.
Then, we can write:
Thus, there are 40 students in the class.
Answer:
A) 277 million years
Step-by-step explanation:
Here, decay of U-238 is first order reaction. (since most of the nuclear decays are first order).
so, the equation t = × ln(
)
where, t = time from start of reaction
k = reaction constant
A(0) = initial concentration; A = present concentration.
⇒ 4.5 billion = 4500 million years = × ln2.
Now, given 95.82% of parent U-238 isotope is left.
⇒ t = × ln(
)
t = × ln(
)
⇒ t ≅ 277 million years.
Answer:
Step-by-step explanation:
You have to divide this by "2"