In a large lecture course, the scores on the final examination followed the normal curve closely. The average score was 60 points and one fourth of the class scored between 50 and 70 points. The standard deviation of the scores was

The value is  

Step-by-step explanation:

From the question we are told that

    The  average score is  

Generally the probability that    of the class score is between 50 and 70 points is mathematically represented as

So

=>  

=>  

From the normal distribution table the critical value of  0.25 for a two tailed test is z= 0.318

So

=>  

3/4 ÷ 3/4

step-by-step explanation:

basically divide any proper fraction with itself to fit the criteria.

so if we are using 3/4, then:

3/4 ÷ 3/4 = 1

so 1 is the quotient.

and the numerators for both these fractions is 3.   and if we divide the numerators:

3 ÷ 3 = 1

we see that quotient is equal to our original quotient as well.