Hypoxia and Medicine

Algebra Help needed!!!1?

1- The oxygen saturation level of a river is found by dividing the amount of dissolved oxygen the river water currently has per liter by the dissolved oxygen capacity per liter. If the river currently has 7.3 milligrams of dissolved oxygen per liter of water and the dissolved oxygen capacity is 9.8 milligrams per liter, What is the oxygen saturation level, to the nearest percent. 2- If a marble is randomly chosen from a bag that contains exactly 8 red marbles, 6 blue marbles, and 6 white marbles, what is the probability that the marble will not be white? 3- So far, a student has earned the fallowing scores on four 100 points tests this grading period:65,73,81 and 82. What score must the student earn on the fifth and last 100 point test of the grading period to earn an average grade of 80 for the 5 tests. 75,76,78,99 OR THE student can't earn an average of 80. Please show me the process not just the answers. At least tell me how todo them so I can learn to solve those. Thanks a lot!!1

Public Comments

1. 2. Total: 8 + 6 + 6 = 20 Prop. everything but white. 8 + 6 = 14 14/20 = 7/10; or 7:10
2. 1. The problem statement tells you that the "capacity" is divided into the "amount", so you simply need to identify the two numbers and divide. The given "amount" is 7.3mg, and the given "capacity" is 9.8mg. So, the O2 saturation is: 7.3/9.8 = 0.7449 or 74% 2. You have 8 red, 6 blue, and 6 white, a total of 20 marbles. The number of non-whites is 8 red, plus 6 blue, or 14 non-white. The probability of drawing a non-white is 14/20, or 0.7, or 70%. 3. Let "x" be the score on the last test. The average would be calculated as follows: Avg = (65 + 73 + 81 + 82 + x)/5 = 80 301 + x = 80*5 = 400 x = 400 - 301 = 99
3. 1. You do like the problem tells you to. You divide (amount of dissolved oxygen the water has per liter) / (dissolved oxygen capacity per liter) The numbers are given; (7.3 mg/L) / (9,8 mg/L) = 0,44898. You however want the answer as a percentage, so you multiply the answer with 100, the result being 44,898% which you round up to 45% like the problem tells you to do. 2. In these types of problems, just think clearly and imagine the odds. You have a bag with a total of 8+6+6 = 20 marbles. 6 of those 20 marbles are white. You do NOT want a white marble. Therefore you only want one of the other 14 marbles in the bag. (since 20marbles - 6 white marbles = 14 non-white marbles). So, the odds of you randomly picking a non-white marble are 14/20. (14/20 = 70%, if you want the answer in %) 3. Multiple choice question. If you are in any doubt, just try out all the options given, and if none of them fits, you pick the last option (the student cant earn an average of 80). However there is an easy way to figure this out. First notice that his average grade at the moment is (65+73+81+82)/4 = 301/4 = 75.25. Which means he needs a higher than 80 to raise his average grade to 80. Just by realizing that you can rule out the first 3 options. Leaving 99 or "Not obtainable" as the only viable answers. Since trying 99 is quicker than trying to proof that he can't obtain the grade, that´s the next step. So you want to see if the grade on his next exam is 99 if it will raise his average grade to 80. (Note, that once he's taken that fifth exam, you must divide the sum of the test results by 5, not 4 like I did earlier to find his avarage grade at the moment) (65+73+81+82+99)/5 = 400/5 = 80. The student needs a 99 on his next exam to get the average grade of 80. Hope this helped.
4. I think you can solve the first two without algebra... 1) The question says to divide the current dissolved oxygen (7.3 milligrams) by the dissolved oxygen capacity (9.8 milligrams), and convert to the nearest percent. So: 7.3/9.8= .7448979592 .7448979592*100=percent=74.48... Then you round to the nearest percent. Since the 4 in .48 is less than 5, you round down, and your answer should be 74% 2)The probability is the possibility of the questioned happening over the total possibilities. So: you have 8 red marbles, 6 white marbles, and 6 blue marbles when you draw one marble out of the bag, you are picking one choice out of all the marbles, so first add up all your marbles: 6+6+8=20 Then figure out how many red and blue marbles you have, because that is how many times you could draw a non-white marble: 8+6=14 Then put divide your red+blue marbles by your total marbles to find the probability: 14/20=7/10=70% so you have a seventy percent chance of drawing a non-white marble. 3) x=the test score needed To find the average, you need to add all the scores and divide by the total number of tests Set this up as an equation: (65+73+81+82+x)/5=80 solve: (301+x)/5=80 301+x=400 x=99 I hope that helped, but see if my answers match up with others' before you take them for the truth.