Answer:
a) 0.7734
Step-by-step explanation:
Problems of normal distributions can be solved using the z-score formula.
In a set with mean 
and standard deviation 
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
In this question, we have that:
(a) what proportion of children aged 13 to 15 years old have scores on this test above 83 ?
This is 1 subtracted by the pvalue of Z when X = 83. So
has a pvalue of 0.2266
1 - 0.2266 = 0.7734
The answer is 0.7734
Answer:
B
Step-by-step explanation:
A cylinder is 12 feet high has a diameter of 10 feet in cubic feet
PERFECT application of the general equation of things
that are moving up and down in gravity:
H(t) = H₀ + v₀t + 1/2 g t²
t = time after the toss
H(t) = height at any time after the toss
H₀ = height from which it's tossed
v₀ = initial speed
g = acceleration of gravity
I'm going to call 'UP' = the positive direction .
So ...
H₀ = +40 ft
v₀ = +54 ft/sec
g = -32 ft/sec²
When the object hits the ground, H(t) = 0 .
So you have ...
0 = 40 + 54 t - 16 t²
Let me re-write that for you, to make it a
little easier and more familiar:
- 16 t² + 54 t + 40 = 0
Divide each side by -2 : 8 t² - 27 t - 20 = 0
Now go to your toolbox, pull out your quadratic formula,
solve that quadratic equation, and you'll get the usual two
solutions.
The positive one is the one you want.
The negative one refers to time before the toss, and may be discarded.
