Answer:
Step-by-step explanation:
we are given half-life of PO-210 and the initial mass
we want to figure out the remaining mass <u>after</u><u> </u><u>4</u><u>2</u><u>0</u><u> </u><u>days</u><u> </u>
in order to solve so we can consider the half-life formula given by
where:
- f(t) is the remaining quantity of a substance after time t has elapsed.
- a is the initial quantity of this substance.
- T is the half-life
since it halves every 140 days our T is 140 and t is 420. as the initial mass of the sample is 5 our a is 5
thus substitute:
reduce fraction:
By using calculator we acquire:
hence, the remaining sample after 420 days is 0.625 kg
5% of $50 = 5/100 x 50 = $2.50
Total = 50 + 2.50 = $52.50
The saes tax is $2.50; her total cost of the shirt is $52.50
Answer:
The 85% onfidence interval for the population proportion of new car buyers who prefer foreign cars over domestic cars is (0.151, 0.205).
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of 
, and a confidence level of 
, we have the following confidence interval of proportions.
In which
z is the zscore that has a pvalue of 
.
For this problem, we have that:
Sample of 421 new car buyers, 75 preferred foreign cars. So 
85% confidence level
So 
, z is the value of Z that has a pvalue of 
, so 
.
The lower limit of this interval is:
The upper limit of this interval is:
The 85% onfidence interval for the population proportion of new car buyers who prefer foreign cars over domestic cars is (0.151, 0.205).
Divide the numerator and denominator by their gcf (25)
75/25= 3
100/25= 4
Final answer: 3/4
If we know that Pedro bought 1
pounds of red sand, and 5
pounds of brown sand, and they both cost $4.60, then we just have to add the individual amounts of sand, since they cost the same.
So Pedro bought
lbs of sand overall. Now, we just need to multiply the cost per pound by the total amount of sand he bought.
Pedro spent $31.05 on sand, which is answer choice B.
Hope that helped =)
