To find one tenth of 119.9 just divide 119.9 by 10
Split up the interval [2, 5] into

equally spaced subintervals, then consider the value of

at the right endpoint of each subinterval.
The length of the interval is

, so the length of each subinterval would be

. This means the first rectangle's height would be taken to be

when

, so that the height is

, and its base would have length

. So the area under

over the first subinterval is

.
Continuing in this fashion, the area under

over the

th subinterval is approximated by

, and so the Riemann approximation to the definite integral is

and its value is given exactly by taking

. So the answer is D (and the value of the integral is exactly 39).
Area of a circle = PI x r^2
Area = 3.14 x 11^2
Area = 3.14 x 121
Area = 379.94 square cm.
<u>First problem :</u>
probability to draw a red paper : 42/(42+18)=7/10
In 110 tries one can thus expect to draw 7/10*110=77 red papers
<u>Second problem :</u>
Since for 150 trials (which will give the least error) we have got 135 yellow balls, we can expect twice as much in 300=150*2 trials, which makes 270 yellow balls.