Answer:
C
Step-by-step explanation:
Using the sine ratio in the right triangle and the exact value
sin30° =
, then
sin30° =
=
=
( cross- multiply )
2x = 10 ( divide both sides by 2 )
x = 5 → C
7/7-1/7=6/7 is the rest of work
1/7 work takes 2days
6*1/7=6/7 work takes 6*2days=12days
30 men takes 12 days to finish the rest of work (6/7)
18 men takes 18*12/30= 7.2days
Answer:
The probability that a call last between 4.2 and 4.9 minutes is 0.4599
Step-by-step explanation:
Let X be the length in minutes of a random phone call. X is a normal distribution with mean λ=4.2 and standard deviation σ=0.4. We want to know P(4.2 < X < 4.9). In order to make computations, we will use W, the standarization of X, given by the following formula

We will use
, the cummulative distribution function of W. The values of
are well known and the can be found in the attached file

We conclude that the probability that a call last between 4.2 and 4.9 minutes is 0.4599
<h2>First Question:</h2><h3>Given: </h3>
2 km = 1 cm
<h3>To Find:</h3>
The length of the road of 15 km.
<h3>Solution:</h3>
2 km = 1 cm
1 km = 1/2 = 0.5 cm
15 km = 0.5 × 15 = 7.5
<h2>Answer: </h2>
The length of the road is <u>7.5 cm</u>.
Therefore, <u>Option D. 7.5 cm</u> is correct.