21 a)
range
1
57
A group of students were given a spelling test.
The table shows their marks.
Mark
b)
Frequency
students
6
5
c)
a) Work out the range of the marks.
mean
8.13
+
7
4
8
7
Submit Answer
b) How many students are in the group?
9
10
c) Work out the mean mark of the group.
10

Step-by-step explanation:

How many students are in the group? 7

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this