Is means equals. The number before the words Less than means that number is subtracted from that number. 3 times a number, we don’t know the number so we use a variable, 3x. So..........
3x-5=10
Answer:

Step-by-step explanation:
Answer:
The PMF of B is given by
P(B=0) = 0.7
P(B=1) = 0.16
P(B=2) = 0.08
P(B=3) = 0.04
P(B=4) = 0.02
Step-by-step explanation:
Let x denote P(B=1), we know that
P(B=0) = 1-0.3 = 0.7
P(B=1) = x
P(B=2) = x/2
P(B=3) = x/4
P(B=4) = x/8
Also, the probabilities should sum 1, thus
0.7+x+x/2+x/4+x/8 = 1
15x/8 = 0.3
x = 0.16
As a result, the PMF of B is given by
P(B=0) = 0.7
P(B=1) = 0.16
P(B=2) = 0.08
P(B=3) = 0.04
P(B=4) = 0.02
Solution: We are given:


Now let's find the estimated value of standard deviation using the range rule of thumb. According to range rule of thumb, the estimate of standard deviation is:

Therefore the estimated standard deviation is 0.690
is this an acceptable approximation?
Answer: c. Yes, because the error of the range rule of thumb's approximation is less than 15%.
Explanation:
The difference between estimated standard deviation and actual standard deviation is:
0.807 - 0.690 = 0.117
Now let's find the percentage of error
.
Therefore, the error of the range rule of thumb's approximation is less than 15%.