A substance decays so that the amount A of the substance left at time t is given by: A = A0 ∙ (0.8)t where A0 is the original amount of the substance. What is the half-life (the amount of time that it takes to decay to half the original amount) of this substance rounded to the nearest tenth of a year? 3.1 0.6 2.5 1.6

Scores on a university exam are normally distributed with a mean of 78 and a standard deviation of 8. the professor teaching the class declares that a score of 70 or higher is required for a grade of at least “c.” using the 68-95-99.7 rule, what percentage of students failed to earn a grade of at least “c”?

Reinel saves 30% of every pay check. his paycheck last week was 560$. how much did reniel save last week?

Paula makes stained-glass windows and sells them to boutique stores. if her costs total $12,000 per year plus $4 per window for the frame. how many windows must she produce to earn a profit of at least $48,000 in one year if she sells the windows for $28 each? 1. define a variable for the situation. 2. write an inequality that represents her profit. note: revenue is money coming in. cost is money going out. profit is the difference between the revenue and the cost. in other words: revenue - costs profit 3.using words, describe how many windows she must sell to have a profit of at least $48,000.