Part a is correct.
Part b can be done a couple ways.
1) Use binomial distribution. p = 0.2, n = 144
P(x>3) = 1 - P(x=0) -p(x=1) -p(x=2) -p(x=3)
where
2) Assume a normal distribution with mean = 28.2, stdev = 4.8
Look up z-value in normal table to find probability.
Hope that helps.
Answer:
Just hope for the best
Step-by-step explanation:
draw a rectangle around it:
the widest part is from about -3 to 2 which is 5 units wide
height is from 3 to -4, which is 7 units
5*7 = 35
the top and bottom are angled so you can subtract a little for that
so I would estimate around 32 square units
Answer:
61,239,550
Step-by-step explanation:
We let the random variable X denote the IQ scores. This would imply that X is normal with a mean of 100 and standard deviation of 17. We proceed to determine the probability that an individual chosen at random from the population would be a genius, that is;
Pr( X>140)
The next step is to evaluate the z-score associated with the IQ score of 140 by standardizing the random variable X;
The area to the right of 2.3529 will be the required probability. This area from the standard normal tables is 0.009314
From a population of 6,575,000,000 the number of geniuses would be;
6,575,000,000*0.009314 = 61,239,550
we know that
1) Lily swims a 
-meter race
2) She swims the first half in 
seconds
3) She swims the second half in 
seconds
so
To find the total time to swim the whole race sum the time in the first half plus the time in second half
therefore
<u>the answer is</u>
