2x^2+7x-4=0
Δ=7^2-4*2*(-4)
Δ=49+32
Δ=81
x1=(-7+V81)/4=(-7+9)/4=2/4=1/2
x2=(-7-9)/4=-16/4=-4
the solutions: x1= 1/2 and x2= - 4
Answer:
0.4353 = 43.53%
Step-by-step explanation:
The times are exponentially distributed, so let's call n the mean, and x the time of transaction. The times of the transaction occurs in a certain time is:
So, the probability that a car complete the transaction in less than 4 minutes, is 1 less the times it does it at 4 minutes:
P = 1 - 
P = 0.4353
P = 43.53%
Answer:
The sampling method used is a stratified sampling method
Step-by-step explanation:
sampling is the selection of a predetermined representative subpopulation from a larger population, to estimate the characteristics of the whole population.
Stratified sampling: Here, the total population are divided into subcategories (strata) before sampling is done. The strata are formed based on some common characteristics. In our example, the times of the day (morning, afternoon and evening) has widely varying atmospheric conditions which will add biases to the measurement of air quality. For example, the air in the morning if compared to the afternoon in an industrial area may be purer because of minimal industrial activity, hence effective comparison will be made by stratification.
The total amount of tax on her purchases to the nearest cent will be $9.97
<em><u>Explanation</u></em>
Marcella Heinz purchased office supplies for $107.64 and then she purchased an English-Spanish dictionary for $16.95
So, the total amount of her purchases 
On the total amount of the purchases, she paid state sales tax of 7.5% and the county tax of 0.5%
So, the <u>amount of the state sales tax</u> 
and the <u>amount of county tax</u> 
Thus, the total amount of tax on her purchases 
<em>(Rounded to the nearest cent)</em>
Answer:
Karen
Step-by-step explanation:
8 gallons of ice cream at $5 per gallon will cost $40. 5 paperback novels at $8 per novel will also cost $40. Only Karen has a budget sufficient to cover the $40+40 = $80 total.
