A negative times a negative is a positive. I am not sure if that's the question, but hopefully that helps if it was.
Answer: {x,y} = {27/4,-47/8}
Answer:
2,674.14 g
Step-by-step explanation:
Recall that the formula for radioactive decay is
N = N₀ e^(-λt)
where,
N is the amount left at time t
N₀ is the initial amount when t=0, (given as 42,784 g)
λ = coefficient of radioactive decay
= 0.693 ÷ Half Life
= 0.693 ÷ 18
= 0.0385
t = time elapsed (given as 72 years)
e = exponential constant ( approx 2.7183)
If we substitute these into our equation:
N = N₀ e^(-λt)
= (42,787) (2.7183)^[(-0.0385)(72)]
= (42,787) (2.7183)^(-2.7726)
= (42,787) (0.0625)
= 2,674.14 g
Answer: The Median: 78, The First Quartile: 63, and The Third Quartile: 99
Step-by-step explanation: Ok, so let's put the data set from least to greatest....
(63, 63, 76,) (77, 79,) (84, 99, 99)
First Quartile Third Quartile
First, let's find the median, since you made a little mistake...
77 + 79 = 156
156 ÷ 2 = 78
The median is 78!
Now, let's determine the first quartile and the third quartile.
For the the first quartile/third quartile it'll be the middle number, if it's even we'll do the same extra step just like we'll do for the median. In this case it's not even therefore...
First Quartile: 63
Third Quartile: 99
I hope this helps!