Answer:
Yes, the ratios do form a proportion.
Answer:

Step-by-step explanation:
The time constant of the isotope is:


The decay of the isotope is described by the following model:

Now, the time is cleared in the equation:



Answer:
4.39% theoretical probability of this happening
Step-by-step explanation:
For each coin, there are only two possible outcomes. Either it lands on heads, or it lands on tails. The probability of a coin landing on heads is independent of other coins. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which
is the number of different combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
Theoretically, a fair coin
Equally as likely to land on heads or tails, so 
10 coins:
This means that 
What is the theoretical probability of this happening?
This is P(X = 2).


4.39% theoretical probability of this happening
Answer:
54 pounds
Step-by-step explanation:
To find out how much flour is needed to make 9 cakes, we first need to find out how much much flour is needed to make 1 cake. For that, we need to divide 6 by 36. That will give you 6. Now that we know how much flour is needed to make 1 cake, we will just have to multiply 6 by 9 to find out how much flour is needed to make 9 cakes. That will give you 54 pounds, which is your final answer.
Answer:
2x - 4
Step-by-step explanation:
a number = x
x is being multiplied to 2
4 is being subtracted from 2 times x
Multiplication is first.
2x - 4