Answer:
Amount of Niobium-91 initially
= 300/91 =3.2967mol
2040 years = 3 ×680 = 3 half-lives
therefore, amount left = 0.4121mol
mass of Niobium-91 remaining = 0.4121 ×91 =37.5g
Please give brainliest
Answer:
1.15%
Step-by-step explanation:
To get the probability of m independent events you multiply the individual probability of each event. In this case we have m independent events, each one with the same probability, therefore:


This is a particlar scenario of binomial distribution problem. So the binomial distribution questions are about the number of success of m independent events, where every individual event has the same p probability. In the question we have 20 events and each event has a probability of 80%. The binomial distribution formula is:

n is the number of events
k is the number of success
p is the probability of each individual event
is the binomial coefficient
the binomial coefficient allows to find the subsets of k elements in a set of n elements. In this case there is only one subset possible since the only way to get 20 of 20 correct questions is to getting right all questions (for getting 19 of 20 questions there are many ways, for example getting the first question wrong and all the other questions right, or getting second questions wrong and all the other questions right, etc).

therefore, for this questions we have:

Answer:
A
Step-by-step explanation:
Please ask if you have further questions
Answer:Do you have a pic of the map? It would make it easier to solve if I could see the map. Its basic area. A=base times height. If the park is 50 m long and is a square, you would do 50 times 50=2500
tep-by-step explanation:
Answer:
Step-by-step explanation:
Since the box contains a cylinder, the height of the box must be gt; = cylinder height
And the area at the bottom of the box is definitely larger than the area at the bottom of the cylinder.
The area at the bottom of the cylinder is PI r squared,
If the bottom of the box is a square, then the area of the bottom is 4r^2, whereas the bottom tends to be polygon, which is equivalent to cutting the circle into equal parts by circle cutting.
So the area at the bottom of the box is
,
It follows that the volume of the box is greater than the volume of the cylinder