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1) If several tests are administered, and the class average is always below the passing grade, does that mean one person will fail?
2) If you were given a 73% average on one test and a 78% average on another, and noone got above 95% on either test, what is the probability that one person failed both tests? Curb Chain ( talk) 03:38, 22 December 2012 (UTC)
The answer to the first question is yes: at least one person will fail. For the class average to be below the passing grade p, the sum of n students' scores on the test has to be ≤ np–1; over k tests the cumulative score of all students combined has to be ≤ knp–k. On the other hand, for each student to get a passing average, each student has to get a cumulative score on all k tests combined of at least pk, so the cumulative score of all students combined has to be ≥ pkn. Since these inequalities contradict each other, someone has to fail. Duoduoduo ( talk) 21:05, 22 December 2012 (UTC)
Given a rational function , is there a way to determine whether there is an electrical circuit built of resistors, capacitors, and inductors (ideal and with positive resistance/capacitance/inductance) which its impedance is , where is the angular frequency of the source (for any )? (I know this is sounds physical, but I think the problem is to determine which functions are possible as impedance and which functions are not, and this is more "mathematical", as it requires some proof) -- 77.125.85.139 ( talk) 19:21, 22 December 2012 (UTC)
Mathematics desk | ||
---|---|---|
< December 21 | << Nov | December | Jan >> | December 23 > |
Welcome to the Wikipedia Mathematics Reference Desk Archives |
---|
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages. |
1) If several tests are administered, and the class average is always below the passing grade, does that mean one person will fail?
2) If you were given a 73% average on one test and a 78% average on another, and noone got above 95% on either test, what is the probability that one person failed both tests? Curb Chain ( talk) 03:38, 22 December 2012 (UTC)
The answer to the first question is yes: at least one person will fail. For the class average to be below the passing grade p, the sum of n students' scores on the test has to be ≤ np–1; over k tests the cumulative score of all students combined has to be ≤ knp–k. On the other hand, for each student to get a passing average, each student has to get a cumulative score on all k tests combined of at least pk, so the cumulative score of all students combined has to be ≥ pkn. Since these inequalities contradict each other, someone has to fail. Duoduoduo ( talk) 21:05, 22 December 2012 (UTC)
Given a rational function , is there a way to determine whether there is an electrical circuit built of resistors, capacitors, and inductors (ideal and with positive resistance/capacitance/inductance) which its impedance is , where is the angular frequency of the source (for any )? (I know this is sounds physical, but I think the problem is to determine which functions are possible as impedance and which functions are not, and this is more "mathematical", as it requires some proof) -- 77.125.85.139 ( talk) 19:21, 22 December 2012 (UTC)