Answer:
<em>Martin saved $75 on the television because of the sale</em>
Step-by-step explanation:
<u>Equations</u>
Let's call x=the original price of the television (before discount).
The television had been on sale for 25% off, this means the discount was:
25% of x = = 0.25x
The sale price was the original price minus the discount:
x - 0.25x = 0.75x
This is what Martin paid, thus:
0.75x = 225
Dividing by 0.75:
x = 225 / 0.75
x = $300
The original price of the television was $300, and the discount was:
0.25*$300 = $75
Martin saved $75 on the television because of the sale
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.