Answer:
ans - all the snow would been removed ....bcause 4 *2.5 is 10
1) -2.3(x-1.2)=-9.66
2) x-1.2=-9.66+2.3
3) x=-9.66+2.3+1.2
4) x=-7.36+1.2
5) x=-6.16
0.25, 0.50, 0.74. It could be any of these numbers or any number between these numbers.
Answer:
The probability of testing positive for one is 0.20.
The probability of testing negative for one sample is (1-0.2)=0.8.
We only save time when all five are negative, which has a probability of 0.8^5=0.32768.
This means that the expected number of tests is
combined sample tests negative = 1 with probability 0.32768
combined sample tests positive = 1+5 retests = 6 with probability 0.67232
Expected number of tests
=Σ nipi / n
=(1*0.32768+6*0.67232)/5 [divide by 5 because we tested 5 samples]
= 0.87232 < 1
So yes, there is a saving.
Note: In practice, all medical tests are not absolute, i.e. they give false-positives(α) and false-negatives (β). The ratios 1-α and 1-β are respectively measures of specificity and sensitivity.
These two parameters complicate the simplistic evaluation above.
