The are four significant figures.
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.
3.60 / 60cm = .06/cm or 6 cents per centimeter
100cm = 1m
$.06 * 100cm = $6.00 / m
100m = 100 * $6.00
= $600
The equation that does not belong is C because it is the only one that contains exponents
Answer:
a) CD = 41 m
b) 77.32°
c) 1380 square metres
Step-by-step explanation:
We can divide the trapezium as shown in the diagram below.
a) To find CD, we use Pythagoras Rule:


b) To find <BCD, we use trigonometric function SOHCAHTOA:
sin(BCD) = opp / hyp
sin(BCD) = 40 / 41
sin(BCD) = 0.9756
=> <BCD = 77.32°
c) The area of a trapezium is given as:
A = 1/2 (a + b) * h
where h = height = 40 m
a = top length = 30 m
b = bottom length = 39 m
A = 1/2 * (30 + 39) * 40
A = 1/2 * 69 * 40
A = 1380 square metres