The grades received by 200 students follow a normal distribution. then mean of the grades is 70 ,and the standard deviation is 7 the number of students who received a grade greater than 70 is about blank and the number of students who got a grade higher than 84 is about

We know that the total sample is 200, the mean is 70, and the standard deviation is 7.

For the normal distribution, between the mean and one standard deviation, the percentage of the sample is 34.1%, between the mean plus one standard deviation, and the mean plus two standard deviations, the percentage of the sample is 13.6%, and there is a 2.3% from this point in forward.

Then. the total percentage that received a grade greater than 70 is:

34.1% + 13.6% + 2.3% = 50%

So half the students received a grade of 70 or more, and 50% of 200 is:

0.5*200 = 100

Now, the students that have a grade higher than 84 are the ones with two times the standard deviation away from the mean:

Because 70 + 7 + 7 = 70 +14 = 84

So there are 2.3% of students with a grade higher than 84; this is:

0.023*200 = 4.6, that must be rounded (because you can not have a 0.6 of a student)

So around 5 students received a grade higher than 84.

i think the answer is a.