An observation from a normally distributed population is considered "unusual" if it is more than 2 standard deviations away from the mean. There are several contaminants that can harm a city's water supply. Nitrate concentrations above 10 ppm (parts per million) are considered a health risk for infants less than six month of age. The City of Rexburg reports that the nitrate concentration in the city's drinking water supply is between 1.59 and 2.52 ppm (parts per million,) and values outside of this range are unusual. We will assume LaTeX: \mu-2\sigma=1.59μ − 2 σ = 1.59 ppm and LaTeX: \mu+2\sigma=2.52μ + 2 σ = 2.52 ppm. It is reasonable to assume the measured nitrate concentration is normally distributed.

i think c. but don't trust it.

step-by-step explanation:

arrange the equations with like terms in columns.

analyze the coefficients of x or y.

add the equations and solve for the remaining variable.

substitute the value into either equation and solve.

check the solution.

step-by-step explanation:

30 miles

step-by-step explanation:

we know that 60 seconds equals 1 minute and 60 minutes 1 hour

44 ft       60 sec     60 min     158400   ft

  *   *   =

1 sec       1 min       1 hour         hour

we know that there are 5280 ft per mile

158400   ft       1 mile         30 miles

  *   =

1   hour               5280 ft     1 hour

so in 1 hour   it can travel 30 miles

the correct option is 2.

step-by-step explanation:

according to the given information triangle abc is a right angle triangle with right angle at a. segment ab is 5 and segment ac is 7. point d is on segment bc and angles adb and adc are right angles.

it is given that triangles abd, cad, and cba are similar.

two triangles are similar if their corresponding sides are proportional.

in triangle cba, using pythagoras theorem

                      )

triangle abd and cba are similar,

                            (2)

triangle cad and cba are similar,

                      )

using (1), (2) and (3), we get

hence proved.

therefore option 2 is correct.