## Precalculus (6th Edition) Blitzer

The least amount of percentage is $95$%
First, let $x$ be the grade on the final examination. Then from the asked problem we have the inequality: $\frac{0.86+0.88+0.92+0.84+2x}{6} \geq 0.90$ Next, all we have to do is solve the inequality. $\frac{0.86+0.88+0.92+0.84+2x}{6} \geq 0.90$ $\frac{3.50+2x}{6} \geq 0.90$ Multiply with $6$ on both sides. $\frac{3.5+2x}{6}\times6 \geq 6\times0.90$ $3.50+2x \geq 5.40$ Subtract $3.50$ on both sides. $3.50+2x-3.50 \geq 5.40-3.50$ $2x \geq 1.9$ Divide with $2$ on both sides. $\frac{2x}{2} \geq \frac{1.9}{2}$ $x \geq 0.95$ Which is our solution.