Mean, m = 18 in
Standard deviation, SD = 2.2 in
Range: 16 ≤ X ≤ 21 in
Calculating Z value,
Z = (X-m)/SD
Then,
Z1 = (16-18)/2.2 ≈ -0.91
Z2 = (21-18)/2.2 ≈ 1.36
From Z table, and at Z1 = -0.91, and Z2 = 1.36;
P(16) = 0.1814
P(21) = 0.9131
Therefore,
P(16≤X≤21) = 0.9131 - 0.1814 = 0.7317
The probability that a child selected randomly measures between 16 and 21 in is 0.7317.
Answer:
90 mi/h
Step-by-step explanation:
Given,
For first 30 miles, her speed is 30 miles per hour,
Let x be her speed in miles per hour for another 30 miles,
Since, here the distance are equal in each interval,
So, the average speed of the entire journey


According to the question,



Hence, she needs to go 90 miles per hour for remaining 30 miles.
First of all, this problem is properly done with the Law of Cosines, which tells us

giving us a quadratic equation for b we can solve. But let's do it with the Law of Sines as asked.

We have c,a,A so the Law of Sines gives us sin C

There are two possible triangle angles with this sine, supplementary angles, one acute, one obtuse:


Both of these make a valid triangle with A=20°. They give respective B's:


So we get two possibilities for b:



Answer: 2.3 units and 7.8 units
Let's check it with the Law of Cosines:


There's a shortcut for the quadratic formula when the middle term is 'even.'




Looks good.
Step-by-step explanation:
hope you can understand