# Problem Set 1(retry)

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MAT 117- Problem Set 1 - Unit A Directions : Complete the problems on the answer sheet provided or on your own blank paper. Create a PDF file of your work and upload it to the Canvas assignment. (Only pdf formatted files are allowed by Canvas). Show all work. 1. Twenty percent of Jennie's skin cells were sun burned when she went boating at Roosevelt Lake. If 3.7 × 10 !! of her skin cells were sun burned then, how many skin cells were not sun burned? (6 points) 1.85x10^12 - 3.7x10^11 = 1.48x10^12 2. The equation for the future value of a simple interest investment is given by the equation A = P + P r t . Solve this equation for P . (4 points) P = A/1+RT 3. The pressure, temperature, and volume of an ideal gas are related by the equation ࠵? = !" #\$ . Solve this equation for T , which is the temperature in degrees Kelvin. (4 points) T = PV/Rn
4. Xavier and Yifei have been married for exactly 10 years. Yifei is seven years older than Xavier. Now the sum of their ages is 67. How old was Yifei when they were married? (6 points) a. Write an equation that represents the unknown ages in terms of Yifei's age when they were married. (Y =Yifei's age when married, X = Xavier's age when married) Y = x+7 X = y-7 (y+10)+(y-7+10) = 67 Y+10 + Y+3 2y+13=67 2y=54 Y=27 b. Determine how old Yifei was when Yifei and Xavier were married. (Solve your equation(s) for Y) 27 Years old. 5. The cost of cleaning up pollution in a stream is given by ࠵? = %&''' ('')* , where C is the cost in dollars to clean p percent of the stream. (For instance, when p is 20, then the formula will calculate the cost to clean up 20 percent of the stream.) p must be greater than or equal to zero and p must be less than what number? Why? (5 points) P must be greater than zero because there is always going to be pollution to clean up, and an unreleastic number would be zero because there is no chance.