Answer to Question #103779 in Statistics and Probability for MBALI

Question

To Obtain Grade A,Gumede must achieve an average of at aleast 75 in six tests.If his average mark for the first is 73, what is the lowest mark he can get in his test, in order to obtain A, Gumede has to get the aversge

Answer 1

To obtain Grade A, Gumede must achieve an average of at least 75 in six tests. If his average mark for the first five tests is 73, what is the lowest mark he can get in his test and still obtain Grade A? 

The average is equal to the sum of values divided by the number of values.

If the average in first five tests is 73, then the sum for the first five tests

$$S_5=73\cdot5=365$$

Let $x$ be the mark for the last test. In order to obtain A, Gumede has to get the average

$${S_5+x\over 6}\geq75$$

$${365+x\over 6}\geq75$$

Solve for $x$

$$x\geq75\cdot6-365$$

$$x\geq85$$

The lowest mark that Gumede can get in his test and still obtain Grade A is $85.$