Step-by-step explanation:
sin∅=-3/4 in 4 quadrant which sine is negative there
using soh cah toa
sin=opp/hyp
where our opp=-3 and our hyp=4
using pythagoras theorem
hyp²=opp²+adj²
(4)²=(-3)²+adj²
16=9+adj²
16-9=adj²
adj²=7
adj=√7
from soh cah toa
cos∅=adj/hyp
cos∅=√7/4
Answer:

--- Variance
Step-by-step explanation:
Given

Solving (a): Calculate the mean.
The given data is a grouped data. So, first we calculate the class midpoint (x)
For 51 - 58.

For 59 - 66

For 67 - 74

For 75 - 82

For 83 - 90

So, the table becomes:

The mean is then calculated as:



-- approximated
Solving (b): The sample variance:
This is calculated as:

So, we have:


-- approximated
Step-by-step explanation:
when means of more than two groups are to be compared, ANOVA is perferred