Answer:
Step-by-step explanation:
basicallyi you want to find a common denominator before you add them up. the common denominator in this case would be 20, since it's the first common multiple all of them share
50/20 plus 72/20 plus 55/20
177/20 would be your answer
Answer:
Credit remaining after 21 minutes = $30.4
Step-by-step explanation:
Credit remaining on a phone card is a linear function of the total calling time.
When graphed, let the linear function representing the line is,
y = mx + b
Where 'm' = slope of the line
b = y-intercept
From the graph,
Slope of the line = -0.12
y = -0.12x + b
If this line passes through a point (33, 28.96),
28.96 = -0.12(33) + b
b = 28.96 + 3.96
b = 32.92
Therefore, the linear function is,
f(x) = -0.12x + 32.92
where x = calling time
Credit left in the card after 21 minutes,
f(21) = -0.12(21) + 32.92
= -2.52 + 32.92
= $30.4
There are 
ways of drawing a 4-card hand, where
is the so-called binomial coefficient.
There are 13 different card values, of which we want the hand to represent 4 values, so there are 
ways of meeting this requirement.
For each card value, there are 4 choices of suit, of which we only pick 1, so there are 
ways of picking a card of any given value. We draw 4 cards from the deck, so there are 
possible hands in which each card has a different value.
Then there are 
total hands in which all 4 cards have distinct values, and the probability of drawing such a hand is
Answer:
The probability of Javier volunteers for less than three a month is 25%
Step-by-step explanation:
According to the questions,
The probability of Javier to attend exactly 5 events :-
P ( x = 5 ) = 25% = 
The probability of Javier to attend exactly 4 events :-
P ( x = 4 ) =
The probability of Javier to attend exactly 3 events :-
P ( x = 3 ) =
The probability of Javier to attend exactly 2 events :-
P ( x = 2 ) = 
The probability of Javier to attend exactly 1 events :-
P ( x = 1 ) = 
The probability of Javier to attend no events :-
P ( x = 0 ) =
Now we have to calculate the probability of Javier volunteers for less than three P ( x < 3 ).
P ( x < 3 ) = P ( x = 0 ) + P ( x = 1 ) + P ( x = 2 )
P ( x < 3 ) = 
= 
= = 0.25 = 25 %.
