Normal-travel DATA:
distance = 240 km
rate = x km/h
time = d/r
= 240/x hrs
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Bad weather DATA:
distance = 240 km
rate = (x-20) km/h
time = 240/(x-20) hrs
______________________
Bad time - normal time = 2 hrs
240/(x-20) - 240/x = 2
120/(x-20) - 120/x = 1
120x -120(x-20) = x(x-20)
20 = x^2 -20x
x^2 - 20x - 20 = 0
x = [20 +- sqrt(20^2 - 4*1*-20)]/2
x = [20 +- sqrt(480)]/2
x = [20 +- 4sqrt(30)]/2
x = 10 +- 2sqrt(30)
The answer is 16, all you must do is substitute x with the given value then solve, so 23-7
Answer:
It is correct
Step-by-step explanation:
20 + 30 = 50
Probability = no of outcomes / total outcomes
First draw = no of blue mables / total mables = 3 / (4 + 3 + 3) = 3/10
For the second draw, since there was no replacement of the first draw, the blue mables has reduced by one, and the total mables has reduced by one.
Second draw = no of remaining blue mables / total remaining mables = 2/9
Probability for both draws = 3/10 x 2/9 = 1/15
