Which one do you need help with
57.29 you do 48.55 times .18 which =8.74 then add the tip with the initial cost 8.74+48.55 =57.29 to get your answer 57.29
3. (a)
Add the three totals.
Total sales for all three: $2030 + $1540 + $1800 = $5370
Now divide each person's sales by the total sales to find each person's fraction of the sales.
Lola: 2030/5370
Ahmed: 1540/5370
Tommy: 1800/5370
3. (b)
Multiply each fraction from part (a) by $100.
Lola: 2030/5370 * $100 = $37.80
Ahmed: 1540/5370 = $28.67
Tommy: 1800/5370 = $33.52
Answer:
a) 0.2416
b) 0.4172
c) 0.0253
Step-by-step explanation:
Since the result of the test should be independent of the time , then the that the test number of times that test proves correct is independent of the days the river is correct .
denoting event a A=the test proves correct and B=the river is polluted
a) the test indicates pollution when
- the river is polluted and the test is correct
- the river is not polluted and the test fails
then
P(test indicates pollution)= P(A)*P(B)+ (1-P(A))*(1-P(B)) = 0.12*0.84+0.88*0.16 = 0.2416
b) according to Bayes
P(A∩B)= P(A/B)*P(B) → P(A/B)=P(A∩B)/P(B)
then
P(pollution exists/test indicates pollution)=P(A∩B)/P(B) = 0.84*0.12 / 0.2416 = 0.4172
c) since
P(test indicates no pollution)= P(A)*(1-P(B))+ (1-P(A))*P(B) = 0.84*0.88+ 0.16*0.12 = 0.7584
the rate of false positives is
P(river is polluted/test indicates no pollution) = 0.12*0.16 / 0.7584 = 0.0253
