
Re-write with common denominator, in this case 6:

Add:
To find the lower quartile take the number of terms=n=12
to find the lower quartile take the equation (n+1)/4= 3.25
this means that the lower quartile will be at the 3.25th position int he sequence when all the terms are ordered from smallest to largest. so when ordered: 12 19 19 19.5 20 28 28 28.5 34 36 45 45
so the lower quartile is between 19 and 19.5 exactly 19.125
Answer: 20
Step-by-step explanation:
We assume that the heights of boys in a high school basketball tournament are normally distributed.
Given : Mean height of boys :
inches.
Standard deviation:
inches.
Let x denotes the heights of boys in a high school basketball tournament .
Then the probability that a boy is taller than 70 inches will be :-
![P(x> 70)=1-P(x\leq70)\\\\=1-P(\dfrac{x-\mu}{\sigma}\leq\dfrac{70-70}{2.5})\\\\=1-P(z\leq0)=1-0.5=0.5\ \ \text{[by using z-value table]}](https://tex.z-dn.net/?f=P%28x%3E%2070%29%3D1-P%28x%5Cleq70%29%5C%5C%5C%5C%3D1-P%28%5Cdfrac%7Bx-%5Cmu%7D%7B%5Csigma%7D%5Cleq%5Cdfrac%7B70-70%7D%7B2.5%7D%29%5C%5C%5C%5C%3D1-P%28z%5Cleq0%29%3D1-0.5%3D0.5%5C%20%5C%20%5Ctext%7B%5Bby%20using%20z-value%20table%5D%7D)
Now, the expected number of boys in a group of 40 who are taller than 70 inches will be :-

Hence, the expected number of boys in a group of 40 who are taller than 70 inches=20
7(2+x)= 7×2=14 . 7× x =7x