You need to understand that you're solving for the average, which you already know: 90. Since you know the values of the first three exams, and you know what your final value needs to be, just set up the problem like you would any time you're averaging something.
Solving for the average is simple:
Add up all of the exam scores and divide that number by the number of exams you took.
(87 + 88 + 92) / 3 = your average if you didn't count that fourth exam.
Since you know you have that fourth exam, just substitute it into the total value as an unknown, X:
(87 + 88 + 92 + X) / 4 = 90
Now you need to solve for X, the unknown:
87
+
88
+
92
+
X
4
(4) = 90 (4)
Multiplying for four on each side cancels out the fraction.
So now you have:
87 + 88 + 92 + X = 360
This can be simplified as:
267 + X = 360
Negating the 267 on each side will isolate the X value, and give you your final answer:
X = 93
Now that you have an answer, ask yourself, "does it make sense?"
I say that it does, because there were two tests that were below average, and one that was just slightly above average. So, it makes sense that you'd want to have a higher-ish test score on the fourth exam.
Answer: {y,x} = {-11/3,-1/3} i hope this helps
Step-by-step explanation:
Answer:
a. π(9^2)(9) - (1/3)(9^2)(9)
step-by-step explanation:
we assume that container a is the whole cylinder, and that container b is the cylinder with the cone carved out.
the formula for the volume of a cylinder is
vcyl = πr²h
the formula for the volume of a cone is
vcon = (1/3)πr²h
here, we have r=h=9 in both cases, and we want to find the difference of volumes. filling in the numbers gives
vcyl - vcon = π(9²)(9) - (1/3)(9²)(9) . . . matches choice a
comment on notation
exponents rarely get copied properly from other applications to brainly, so some editing may be required. if you don't use the equation editor or special mathematical symbols, the plain-text form for an exponent is
(base)^(exponent) . . . the exponent is signified by a caret (^)
note that grouping symbols may be required. if the exponent has an arithmetic operation in it, then it needs parentheses:
√(x) = x^(1/2)
(x^a)(x^b) = x^(a+b)
the use of the word "over" to signify a fraction is unnecessary and ambiguous. the forward slash (/) is usually used for that purpose. as with the caret, any numerator or denominator consisting of more than a single number or letter needs parentheses: (1/a) + (1/b) = (a+b)/(ab). even if you know that the denominator is a single number, as in 1/3, it understanding to put the fraction in parentheses so the appropriate interpretation is clear. (see above for examples. many people write 1/x+1 when they mean 1/(x+1), so if you mean (1/x)+1, it is to write it that way--even though that is how it should be interpreted.)
Answer:
The answer is 16.5 meters in 10 seconds
Step-by-step explanation:
First you divide 99 by 60 seconds
When you get 1.65 you multiply it by 10 second.
When you multiply 1.65 by 10 second you get 16.5 meters in 10 seconds
