Scores on an achievement test had an average of 70 and a standard deviation of 10. Serena's score was 85. Assuming the scores have approximately a normal distribution, about what
proportion of students scored lower than Serena?
A.0.93
B.0.07
C.0.84
D.0.69

Is my answer correct? And particularly the graph?

1 number

if we use a graphing calculator, there is only one such number that satisfies the conclusion of the mean value theorem, that is, a number such that

where the right-hand side is the average rate of change of f on the interval [0.5,0.75], which is the slope of the secant line.

in the attached graph, the black line is the secant line which has its slope as the average rate of change of f on [0.5,0.75], while the orange line is the only tangent line to the graph of f in the interval that satisfies the mvt conclusion.

0.85% : )

step-by-step explanation: