Answer:
Step-by-step explanation:
Let x be the random variable representing the the length of newborn babies (in inches). Since it is normally distributed and the population mean and population standard deviation are known, we would apply the formula,
z = (x - µ)/σ
Where
x = sample mean
µ = population mean
σ = standard deviation
From the information given,
µ = 20 inches
σ = 2.6 inches
the probability that a given infant is between 14.8 and 25.2 inches long is expressed as
P(14.8 ≤ x ≤ 25.2)
For x = 14.8,
z = (14.8 - 20)/2.6 = - 2
Looking at the normal distribution table, the probability corresponding to the z score is 0.023
For x = 25.2
z = (25.2 - 20)/2.6 = 2
Looking at the normal distribution table, the probability corresponding to the z score is 0.98
Therefore,
P(14.8 ≤ x ≤ 25.2) = 0.98 - 0.23 = 0.75
These problems are called systems of equations. Basically you have two linear equations and you need to find the values for x and y. In other words, all these equation are lines and our answer will be the exact point that the pair of lines intersect. For example, if we get x=1 and y=2 the lines will intersect at point (1,2). Now that you have some background knowledge here comes the tricks and tactics kid.
We know that we can solve one variable equation easily. For example...
x+1=2
x=1 obviously
Cause we have two variables x and y it is not possible to find a solution. For example, in the equation x+y=10, x=1 when y=9 and x=2 when y=8. There is not correct answer.
So what can we do? We have to make a two variable equation into a one variable equation.
There are two ways to do this: substitution and elimination. I will create a sample problem and then solve it using both methods.
x+y=2
2y-y=1
3)
-3x-5y=-7 -----> -12x-20y=-28
-4x-3y=-2 ------> -12x-9y=-6
-12x-20y=-28
-(-12x-9y=-6)
---------------------
-11y=-22
y=2
-3x-5(2)=-7
-3x=3
x=-1
4) 8x+4y=12 ---> 24x+12y=36
7x+3y=10 ---> 28x+12y=40
28x+12y=40
-(24x+12y=36)
---------------------
4x=4
x=1
8(1)+4y=12
4y=4
y=1
5) 4x+3y=-7
-2x-5y=7 ----> -4x-10y=14
4x+3y=-7
+(-4x-10y=14)
-------------------
-7y=7
y=-1
4x+3(-1)=-7
4x=-4
x=-1
6) 8x-3y=-9 ---> 32x-12y=-36
5x+4y=12 ---> 15x+12y=36
32x-12y=-36
+(15x+12y=36)
--------------------
47x=0
x=0
8(0)-3y=-9
-3y=-9
y=3
7)-3x+5y=-2
2x-2y=1 ---> x-y=1/2 ----> x=y+1/2
-3(y+1/2)+5y=-2
-3y-1.5+5y=-2
2y=-0.5
y=0.25
2x-2(0.25)=1
2x=1.5
x=0.75
Answer:
(x + 1/2)^2 = 289/4
Step-by-step explanation:
x^2+x-72=0
Write like this:
(x + ___)^2 = ___
put 72 on other side
x^2 + x = 72
x^ + x + (1/4) = 72 + (1/4)
(x + 1/2)^2 = 289/4
x + (1/2) = 17/2
For the first two,the probability is 0.4, and for # 3,the probability is .2
Answer:
$3.48 for each pair of socks.
Step-by-step explanation:
It's a little confusing, because it says they're buying 2 socks, but then asks for the price of each of 2 *pairs* of socks. I'm going to believe the first sentence should say they paid for 2 pairs of socks.
They have $10, and get $3.04 in change. So we'll subtract $3.04 from $10 to find out the cost of 2 pairs of socks.
10 - 3.04 = 6.96
Then divide $6.96 by 2 pairs of socks
6.96/2 = $3.48 for each pair of socks.