60% = 0.6
12 / 0.6 = 20
answer 12 is 60% of 20
Answer:
The mean and the standard deviation of the number of students with laptops are 1.11 and 0.836 respectively.
Step-by-step explanation:
Let <em>X</em> = number of students who have laptops.
The probability of a student having a laptop is, P (X) = <em>p</em> = 0.37.
A random sample of <em>n</em> = 30 students is selected.
The event of a student having a laptop is independent of the other students.
The random variable <em>X</em> follows a Binomial distribution with parameters <em>n</em> and <em>p</em>.
The mean and standard deviation of a binomial random variable <em>X</em> are:

Compute the mean of the random variable <em>X</em> as follows:

The mean of the random variable <em>X</em> is 1.11.
Compute the standard deviation of the random variable <em>X</em> as follows:

The standard deviation of the random variable <em>X</em> is 0.836.
Answer:
In the first week, Micah bought 11 gallons of gas.
In the second week, Micah bought 8 gallons of gas.
Step-by-step explanation:
Given:
First week
x gallons of gas at $2.39 per gallon
x gallons = $2.39x
Second week
3 fewer gallons of gas than the first week at $2.49 per gallon
x - 3 gallons = $2.49(x-3)
Total spent = $46.21
$2.39x + $2.49(x-3) = $46.21
2.39x + 2.49x - 7.47 = 46.21
4.88x - 7.47 = 46.21
Add 7.47 to both sides
4.88x - 7.47 + 7.47 = 46.21 + 7.47
4.88x = 53.68
Divide both sides by 4.88
x = 53.68/4.88
= 11
x = 11
First week = x = 11 gallons
Second week
= x - 3
= 11-3
= 8 gallons
Therefore,
In the first week, Micah bought 11 gallons of gas.
In the second week, Micah bought 8 gallons of gas.