Answer:
x = 3 , y = 1
Step-by-step explanation:
2x + y = 7
3x + y = 8
solution
2x + y = 7-----------(1)
3x - y = 8------------(2)
from equation 1
2x + y = 7
y = 7 - 2x-------------(3)
substitute equation 3 into equation 2
3x - y = 8
3x - (7 - 2x) = 8
3x - 7 + 2x = 8
3x + 2x = 8 + 7
5x = 15
divide through by the coefficient of x
5x/5 = 15/5
x = 3
to find y
substitute x into equation 1
2x + y = 7
2(3) + y = 7
6 + y = 7
y = 7 - 6
y = 1
Answer:
44cm
Step-by-step explanation:
Formula for circumference, C = 2πr
where r is the radius
r = C / 2π
=
=44 cm
Answer:
B. DC = 29 and DE = 44.5
Step-by-step explanation:
I honestly don't know how to get DE but because DC has to be 29, the second option is the only right answer
Answer:
The population standard deviation is not known.
90% Confidence interval by T₁₀-distribution: (38.3, 53.7).
Step-by-step explanation:
The "standard deviation" of $14 comes from a survey. In other words, the true population standard deviation is not known, and the $14 here is an estimate. Thus, find the confidence interval with the Student t-distribution. The sample size is 11. The degree of freedom is thus .
Start by finding 1/2 the width of this confidence interval. The confidence level of this interval is 90%. In other words, the area under the bell curve within this interval is 0.90. However, this curve is symmetric. As a result,
- The area to the left of the lower end of the interval shall be .
- The area to the left of the upper end of the interval shall be .
Look up the t-score of the upper end on an inverse t-table. Focus on the entry with
- a degree of freedom of 10, and
- a cumulative probability of 0.95.
.
This value can also be found with technology.
The formula for 1/2 the width of a confidence interval where standard deviation is unknown (only an estimate) is:
,
where
- is the t-score at the upper end of the interval,
- is the unbiased estimate for the standard deviation, and
- is the sample size.
For this confidence interval:
Hence the width of the 90% confidence interval is
.
The confidence interval is centered at the unbiased estimate of the population mean. The 90% confidence interval will be approximately:
.