First, find the z-score:
z = (value - mean) / sdev
= (275 - 280) / 15
= - 0.33
In order to use a standard normal table, we need a positive z-score:
P(z < -0.33) = 1 - P(z < 0.33)
Looking at the table, we find P(z < 0.33) = 0.6293
Therefore:
P(z < -0.33) = 1 - 0.6293 = 0.3707
Hence, you have a probability of about 37% <span>that a randomly selected pregnancy lasts less than 275 days.</span>
Answer:
x = 7; y = 77
Step-by-step explanation:
y = 9x + 14
y = 4x + 49
Since both equations are solved for y, set the two right sides equal and solve for x.
9x + 14 = 4x + 49
5x = 35
x = 7
Sow substitute 7 for x in the first equation and solve for y.
y = 9x + 14
y = 9(7) + 14
y = 63 + 14
y = 77
Answer: x = 7; y = 77
Answer:
7400
Step-by-step explanation:
Answer:
$ (7x+12)
Step-by-step explanation:
We have that,
Price of each cell phone plan = $x
Since, 3 friends pay extra $4 for the plan.
Thus, the amount paid by the three friends is $ 3(x+4).
Now, as the ramaining people do not pay the extra cost and there are 7-3 = 4 people remaining.
Thus, the amount paid by remaining people = $ 4x
Thus, the total cost of the plan will be $ [3(x+4) + 4x] = $ (7x+12).
Hence, the expression for the total cost of the seven plans is $ (7x+12).
