Help me with this Math question please

[myair]

---

Members don't see this ad.

In a given course Ann got 81,85,and 95 for ther preminiary examinations. The final examination is weighed for one-third and the average of the preminiary grades is weighned 2/3 of the final grade. What should the final examination grad be for a semester average of 90?


81+85+ 95 = 261
261/3 = 87
(2/3) 87 = 58

and rest I have no clue, please help???thank you 🙂

 

[lhtran07]

This is what I got:
Semester avg = 2/3(avg. of 3 tests) + 1/3(final exam)

Avg. of 3 tests:
81+85+95 = 261/3 = 87


(2/3)87 + (1/3)x = 90
solving for x gives me: 96

So final exam grade needs to be 96 for semester avg of 90

 

[myair]

Thank you 🙂