Answer:
2401
Step-by-step explanation:
Given that we want to estimate average income in a population.
The standard deviation of income in the population is $1,000
We want confidence interval around our estimate to be +/- $40
i.e Margin of error = 40
We know that margin of error = Std error * Z critical for 95%
i.e. 
Std error = 
Together we get

Answer:
Under 99% confidence level we can say that mean speed of the new chips is greater than that of the old chips
Step-by-step explanation:
: Mean speed of the new chip is the same as the old chip
: Mean speed of the new chip is greater than the old chip
to calculate the z-statistic we can use the formula:
z=
if we put the numbers then
z=
=4.8171
The probability of this z-statistic is < 0.001 Therefore Under 99% confidence level we can say that mean speed of the new chips is greater than that of the old chips
The answer is 10/36 or 27.77%
here’s the working out
Answer:
(a) The probability of more than one death in a corps in a year is 0.1252.
(b) The probability of no deaths in a corps over 7 years is 0.0130.
Step-by-step explanation:
Let <em>X</em> = number of soldiers killed by horse kicks in 1 year.
The random variable
.
The probability function of a Poisson distribution is:

(a)
Compute the probability of more than one death in a corps in a year as follows:
P (X > 1) = 1 - P (X ≤ 1)
= 1 - P (X = 0) - P (X = 1)

Thus, the probability of more than one death in a corps in a year is 0.1252.
(b)
The average deaths over 7 year period is: 
Compute the probability of no deaths in a corps over 7 years as follows:

Thus, the probability of no deaths in a corps over 7 years is 0.0130.
Answer:
See explanation
Step-by-step explanation:
Triangles ΔABC and ΔBAD are congruent. So,
- AB ≅ BA;
- AC ≅ BD;
- BC ≅ AD;
- ∠ABC ≅ ∠BAD;
- ∠BCA ≅ ∠ADB;
- ∠CAB ≅ ∠DBA.
Consider triangles AEC and BED. In these triangles,
- AC ≅ BD;
- ∠EAC ≅ ∠EBD (because ∠CBA ≅ ∠BAD);
- ∠AEC ≅ ∠BED (as vertical angles).
So, ΔAEC ≅ ΔBED. Thus,
AE ≅ EB.
This means that segment CD bisects segment AD.