Answer: The answer is 8.
Step-by-step explanation: The first step is to convert the expression into figures. We shall call the unknown number Y. So if we are told “the square of a number,” that means Y squared, or better still, Y^2. Further we are told “the difference between the square of a number and 40” and that can be written as;
Y^2 - 40.
Next we are told that this expression is equal to 3 times that number (that is 3Y). That can now be written out as follows,
Y^2 - 40 = 3Y
If we move all expressions to one side of the equation, what we would have is,
Y^2 - 3Y -40 = 0
(Remember that when a positive value crosses to the other side of an equation it becomes negative and vice versa)
We now have a quadratic equation
Y^2 -3Y - 40 = 0
By factorizing we now have
(Y -8) (Y + 5) = 0
Therefore Y - 8 = 0 or
Y + 5 = 0
Hence, Y = 8 or Y = -5
Since we are asked to calculate the positive solution, Y = 8
Answer:
He did 9 times 10 instead of 9 times 100.
Answer:
0.3875
Step-by-step explanation:
Given that in a group of college students, the ratio of men to women is 3:1 (i.e., 3 to 1). In a recent survey, 40% of the men in this group selected hiking as their favorite outdoor activity whereas 35% of the women in the group selected hiking as their favorite outdoor activity
From the above information we find that
P(Men) = 0.75 and P(women) = 0.25 (since men:women = 3:1)
Out of men prob for not selecting hiking as their favorite outdoor activity
Out of women prob for not selecting hiking as their favorite outdoor activity
Prob for a randomly selected person that hiking is not his/her favorite outdoor activity = Prob (man and not selected activitiy) + P(women and not selected activity) (since men and women are mutually exclusive and exhaustive)
=
The formula for calculating compound interest with yearly contributions is:
Balance = X*(1 + Y)^n + Z((1 + Y)^(n + 1) - (1 + Y)/Y)
where the balance is the money earned after n years invested
Y is the interest rate as a fraction
Z is the yearly contribution
X is the starting investment
Therefore the calculation for this example is:
Balance = 1200*(1 + 0.05)^48 + 1200((1.05)^49 - (1.05)/05)
= $249,393.5
