Answer:

Step-by-step explanation:
Second one is faster, so let's get rid of it first.
Divide by 2 to make numbers easier, and we get
. You should recognize 81 is 9 squared, and both
and
, when squared, give 81, we have our solution.
Now the first. I can't spot any quick trick to solve it, so quadratic formula it is. Let's rememer it: if
then

Let's bring the first equation in the standard form and calculate the quantity over the square root (usually called with the greek letter delta,
) to the side.

now we can apply the formula:
Let's split the two cases now

Since percent means 'over 100', you can put 42 over 100:

. Since .42 is less than .44, that means that
.44 is your answer.
4/5 is the answer to reduce to the lowest of 16/20
Let

denote the random variable for the weight of a swan. Then each swan in the sample of 36 selected by the farmer can be assigned a weight denoted by

, each independently and identically distributed with distribution

.
You want to find

Note that the left side is 36 times the average of the weights of the swans in the sample, i.e. the probability above is equivalent to

Recall that if

, then the sampling distribution

with

being the size of the sample.
Transforming to the standard normal distribution, you have

so that in this case,

and the probability is equivalent to
