Explanation: To solve for <em>x</em>, we must first isolate <em>x</em> and the division property of equality allows to divide bt 7 on both sides of the equation.
On the left the 7's cancel and on the right, 21 divided by 7 is 3.
The probability that student scored more than 850 we shall proceed as follows: z=(x-μ)/σ where: x=850 μ=750 σ=50 thus z=(850-750)/50 z=2 thus P(x>850)=1-P(x<850)=1-P(z<2)=1-0.9772=0.0228
