in mei lins school, her science teacher gives tests that are marked out of 100. mei lin has an average of 60 marks on her first four science tests. on the fifth test she got 80 marks. what is the average of mei lins marks in science after all five tests?

Ais the answer to your ques

1.   an exact solution requires a radical solution - no decimal approximation.2. (a)4x^3 = 756x^3 = 756/4 = 189x =   cube root of 189 =   5.74   to nearest hundredth answer(b)   189 = 3*3*3*7   so we can write the cube root of 189 as 3∛7 answerchecking (a) 4*(5.74^3 =   756.48   which is very close(b)   4* ((3∛3)^3   = 4*189   = 756   - spot on! 3. i would use solution b because the original question asked for an exact solution.