Answer:
Step-by-step explanation:
Since the sample size is quite large, we can use the z-distribution.
The margin of error is given by
Where n is the sample size, s is the sample standard deviation and 
is the z-score corresponding to a 90% confidence level.
The z-score corresponding to a 90% confidence level is
Significance level = α = 1 - 0.90= 0.10/2 = 0.05
From the z-table at α = 0.05
z-score = 1.645
Therefore, the margin of error is 0.776.
Answer:
Width=6.5 cm
Length=12 cm
Step-by-step explanation:
Step 1: Express the lengths and widths
Width=w
Length=l, but 1 cm less than twice the width=(2×w)-1=2 w-1
Step 2: Solve for the length and width
A=L×W
where;
A=area of the photograph
L=length of the photograph
W=width of the photograph
In our case;
A=91 cm²
L=2 w-1
W=w
91=(2 w-1)w
2 w²-w=91
2 w²-w-91=0, is a quadratic equation
solve for w
w={-1±√(-1²-4×2×-91)}/(2×2)
w=(-1±27)/4
w=(27-1)/4=6.5, or (-1-27)/4=-8
Take w=6.5 cm
L=(2×6.5)-1=13-1=12 cm
Width=6.5 cm
Length=12 cm
Your answer is c
Hope this helps :)
53.55 / 85 = 0.63
0.63 * 100 = 63
63 - 38 = 25
watch was 25 before discount
D
An easier way of doing it mentally is 3 x 25 which is 75 and then 1 x 25 which is 25
