If 4/3 liters of water are enough to water 2/5 of the plants in the house, how much water is necessary to water all the plants i
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19 small mowers and 11 large mowers are sold
<em><u>Solution:</u></em>
Let "a" be the number of small mowers sold
Let "b" be the number of large mowers sold
Cost of each small mower = $ 249.99
Cost of each large mower = $ 329.99
<em><u>30 total mowers were sold</u></em>
Therefore,
a + b = 30
a = 30 - b ------------- eqn 1
<em><u>The total sales for a given year was $8379.70</u></em>
<em><u>Thus we frame a equation as:</u></em>
number of small mowers sold x Cost of each small mower + number of large mowers sold x Cost of each large mower = 8379.70
249.99a + 329.99b = 8379.70 ---------- eqn 2
<em><u>Let us solve eqn 1 and eqn 2</u></em>
<em><u>Substitute eqn 1 in eqn 2</u></em>
249.99(30 - b) + 329.99b = 8379.70
7499.7 - 249.99b + 329.99b = 8379.70
80b = 8379.70 - 7499.7
80b = 880
Divide both sides by 80
b = 11
<em><u>Substitute b = 11 in eqn 1</u></em>
a = 30 - 11
a = 19
Thus 19 small mowers and 11 large mowers are sold
Answer:
a)
And we can find this probability using the normal standard distirbution or excel and we got:
b)
And we can find this probability with this difference:
And in order to find these probabilities we can use tables for the normal standard distribution, excel or a calculator.
Step-by-step explanation:
Previous concepts
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".
a) less than 7 months.
Let X the random variable that represent the length of life of an instrument of a population, and for this case we know the distribution for X is given by:
Where and
We are interested on this probability
And the best way to solve this problem is using the normal standard distribution and the z score given by:
If we apply this formula to our probability we got this:
And we can find this probability using the normal standard distirbution or excel and we got:
b) between 7 and 12 months.
And we can find this probability with this difference:
And in order to find these probabilities we can use tables for the normal standard distribution, excel or a calculator.