Employees that work at a fish store must measure the level of nitrites in the water each day. Nitrite levels should remain lower than 5 ppm as to not harm the fish. The nitrite level varies according to a distribution that is approximately normal with a mean of 3 ppm. The probability that the nitrite level is less than 2 ppm is 0.0918.

Which of the following is closest to the probability that on a randomly selected day the nitrite level will be at least 5 ppm?

(A) 0.0039

(B) 0.0266

(C) 0.0918

(D) 0.7519

(E) 0.9961

And olving for the deviation we got:

And then we want to find this probability:

Using the z score we got:

And using the complement rule and the normal standard distirbution or excel we got:

And the best answer for this case is:

(A) 0.0039

Step-by-step explanation:

For this case we define the random variable X as " The nitrite level" and we know that the distribution of X is given by:

We don't know the deviation. We also know the following condition:

So then we can use the z score formula given by:

We need to find a z score value that accumulates 0.0918 of the area on the right and we got z = -1.330, since P(Z<-1.330) = 0.0918. Then we can set up the following equation:

And olving for the deviation we got:

And then we want to find this probability:

Using the z score we got:

And using the complement rule and the normal standard distirbution or excel we got:

And the best answer for this case is:

(A) 0.0039

2. angles qrt and qst both measures 156 degrees.

step-by-step explanation:  

we have been given a diagram of a circle and we are told that measure of arc qvt is 156 degrees.  

we can see from our given diagram that angle qrt and angle qst subtends to arc qvt.

since we know that angles subtended by the same arc at the circumference are always equal.

by angle subtended by same arc theorem, measure of angle qrt and angle qst will be equal to the measure of arc qvt.

therefore, angles qrt and qst both measures 156 degrees and 2nd statement is the correct choice.

2 & 7

step-by-step explanation:

he climbs 300 ft/hr at a constant rate. the peak is at 1,500 ft.

when going up, he reaches 600 ft in 2 hours. remember, that he is going in a constant rate. divide 600 with 300:

600/300 = 2

assuming that he takes the same route back (meaning that it's a 1500 ft route back, you can solve.

note also that you are solving when he gets back to 600 ft after he reaches the peak.

first, find the amount of hours it takes to get up the peak. divide the total amount (1500), with the ft/her (300) to get the amount of hours (x):

1500/300 = x

x = 5

it takes jamie 5 hours to get up. now, he is returning down, and reaches 600 (his current destination). remember that he climbs at a constant 300 ft/hr. divide 600 with 300:

600/300 = x

x = 2

now add the two numbers together.

x = 5 + 2 = 7

jamie takes 7 hours to go up the mountain and reach his current position when descending.

(total amount/constant rate) = (time).

remember that it is a constant rate, so in total, when he gets back down the mountain, it will take the same amount of time as when he goes up. the total amount for the round trip is: 5 + 5 = 10.

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