The sample std. dev. will be (14 inches) / sqrt(49), or (14 inches) / 7, or 2 inches.
Find the z score for 93.8 inches:
93.8 inches - 91.0 inches 2.8 inches
z = ------------------------------------- = ----------------- = 1.4
2 inches 2 inches
Now find the area under the standard normal curve to the left of z = +1.4.
My calculator returns the following:
normalcdf(-100,1.4) = 0.919. This is the probability that the mean annual precipitation during those 49 years will be less than 93.8 inches.
Hello there! The axis of symmetry is the vertical line where the parabola can be divided and there are two equal halves. The vertex is on that line. The point where this occurs is all in the positive range, so that eliminates B, C, and D. (0.5, 4.25) is the vertex and 0.5 is the axis of symmetry. The answer is A. Your answer is correct.
30 is your mystery answer :)
