simple stuff that a math illetirate doesnt get HELP!!

[vanwaq]

i had two tests part 1 = 75% and part 2 = 25 %.

the two test combined together are worth 25% of my final grade.

I want to know if i got 100% on the first part and 0% on the second part, what would be my mark out of 25% of the final grade ?

what would my mark be if i got 70% on the first part and 0% on the second?

 

[JeffM]

i had two tests part 1 = 75% and part 2 = 25 %.

the two test combined together are worth 25% of my final grade.

I want to know if i got 100% on the first part and 0% on the second part, what would be my mark out of 25% of the final grade ?

what would my mark be if i got 70% on the first part and 0% on the second?

This is a problem concerning weighted averages.

Let's take it in steps.

Part 1 is worth 75% of the test. Part 2 is worth 25% of the test. If q = the percent you got right on the first part and r = the percent you got right on the second part, your percentage score for the test is

\(\displaystyle \dfrac{75 * q + 25 * r}{10000}\)

Let's take your two examples

\(\displaystyle \dfrac{75 * 100 + 25 * 0}{10000} = \dfrac{7500 + 0}{10000} = \dfrac{7500}{10000} = 0.75 = 75\%.\)

\(\displaystyle \dfrac{75 * 70 + 25 * 0}{10000} = \dfrac{5250 + 0}{10000} = \dfrac{5250}{10000} = 0.525 = 52.5\%.\)

Now let's try a harder example You got 80% on part 1 and 90% on part 2.

\(\displaystyle \dfrac{75 * 80 + 25 * 90}{10000} = \dfrac{6000 + 2250}{10000} = \dfrac{8250}{10000} = 0.825 = 82.5\%.\)

Make sense?

 

[vanwaq]

thanks for the help. i want to know what my mark would be out out 25% of the final grade if i got 100% on part 1. Would it be 18 % out 25% etcc....

 

[JeffM]

thanks for the help. i want to know what my mark would be out out 25% of the final grade if i got 100% on part 1. Would it be 18 % out 25% etcc....

I am not sure that I understand your question. What matters toward your final grade is what you got on the entire test, not a part of it. Whatever your score was on the entire test (say 70%) then that represents 0.7 * 0.25 = 0.175 = 17.5% that will be added to the percentages from the other parts of your course.

 

[vanwaq]

I know i got 100% or 80% on the first part of the test
i know i got 0% on the second part of the test.
i know it matters what i get on both parts...

but i want to know if i got 100% on the first part of the test out of 25% of the final grade what would my mark be would it be 18% out of 25% of the final grade or 12% out of 25%.

tahnks agains

 

[JeffM]

I know i got 100% or 80% on the first part of the test
i know i got 0% on the second part of the test.
i know it matters what i get on both parts...

but i want to know if i got 100% on the first part of the test out of 25% of the final grade what would my mark be would it be 18% out of 25% of the final grade or 12% out of 25%.

tahnks agains

100% = 1 This represents score on first part of test
75% = 0.75 This represents weight of first part in scoring the test
25% = 0.25 This represents weight of test in computing final grade

\(\displaystyle 1 * 0.75 * 0.25 = 0.1875 \approx 19\%.\)

If you got 100% on first part of test, that gives you about 19 percentage points toward final grade.

80% = 0.8 This represents score on first part of test
75% = 0.75 This represents weight of first part in scoring the test
25% = 0.25 This represents weight of test in computing final grade

\(\displaystyle 0.8 * 0.75 * 0.25 = 0.15 \approx 15\%.\)

If you got 80% on first part of test, that gives you 15 percentage points toward final grade.

 

[vanwaq]

thanks a lot for all your help. can you believe im 25 years and i finishing my IT degree and i cant do that. math is my weakest subject. its lik my thinking process gets blocked as soon it sees numbers hahah. i have to see visually in my head number to add or subtract and its takes me forever. even like 25 * 83 etc, my litle cousins can do math faster than me. Its b/c my foundation of math got messed up wehn i was little. but i can hack anything hehehhe