Answer:
Step-by-step explanation:
Let x = the age of the youngest child
Let x + 1 = the age of the middle child
Let x + 2 = the age of the oldest child
x + x + 1 + x + 2 = 39
3x + 3 = 39
3x = 36
x = 12 years
Answer:
14. 2384 in²
15. 291.8 in²
Step-by-step explanation:
14. The total surface area consists of the area of two equal triangles and three rectangles.
The area of each triangle is
, which is
. The area of both triangles combined is 336 in².
The area of each of the slanted rectangles is base x height, which is 25x32=800 in². The area of both rectangles combined is 1600 in².
The area of the base rectangle is 14x32=448 in².
Therefore, to find the total surface area, you add the area of each side together: 336+1600+448=2384 in².
15. The equation for the surface area of a cylinder is
.
The radius (r) is 4.6 in and the height (h) is 9.1 in.
Therefore, the surface area is:
in²
Answer:
5.78% probability that exactly 2 of them use their smartphones in meetings or classes.
Step-by-step explanation:
For each adult, there are only two possible outcomes. Either they use their smarthphone in meetings or classes, or they do not. The probability of an adult using their smartphone on meetings or classes is independent of other adults. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which
is the number of different combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
63% use them in meetings or classes.
This means that 
7 adult smartphone users are randomly selected
This means that 
Find the probability that exactly 2 of them use their smartphones in meetings or classes.
This is P(X = 2).


5.78% probability that exactly 2 of them use their smartphones in meetings or classes.
Answer:
10.4
Step-by-step explanation:
√(5--5)²+(0-3)²
√100+9
√109=10.4
Answer:
The value is a statistic, since it is from a sample.
Step-by-step explanation:
If the value is from a population, it is a parameter.
Otherwise, if the value is from a sample, it is a statistic.
In this question:
In a random sample of U.S. households, it was found that 72% have high-speed Internet.
The value is from a sample, so it is a statistic.