Answer:
8 days
Step-by-step explanation:
On day 8, Isabella will save 256 nickels, bringing her total to 510.
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The number of nickels saved on day n is 2^n. The total is 2^(n+1)-2.
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The above can be written down from your knowledge of binary sequences. If you want a more formal development, read on.
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The number of nickels saved on day n is a geometric sequence with first term 2 and common ratio 2. The n-th term of the sequence is ...
an = a1·r^(n-1) = 2·2^(n-1) = 2^n
The sum of n terms of the sequence is ...
S = a1(r^n -1)/(r -1) = 2(2^n -1)/(2-1)
S = 2^(n+1) -2
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We want S > 500, so ...
500 < 2^(n+1) -2
502 < 2^(n+1)
251 < 2^n
log(251) < n·log(2)
n > log(251)/log(2)
n > 7.97 . . . . . . . . 8 days or more to save more than 500 nickels
Step-by-step explanation + Answer:
x = 1st job
y = 2nd job
x + y = 22......x = 22 - y
7x + 8.25y = 171.50
7(22 - y ) + 8.25y = 171.50
154 - 7y + 8.25y = 171.50
-7y + 8.25y = 171.50 - 154
1.25y = 17.50
y = 17.50 / 1.25
y = 14 <== 14 hrs at the 8.25 per hr job
x + y = 22
x + 14 = 22
x = 22 - 14
x = 8 <=== 8 hrs at the 7 per hr job
Step 1: Find the value of one variable in terms of the other.
Step 2: Substitute the value you just found for this variable in the other equation.
Step 3: Use your new value for the second variable to find the first.
Now that we know the values for a and b we can find the value of 4a+b.
Answer:
343
Step-by-step explanation:
7^3=7×7×7=343
If e is equal to 7 just multiply 7 by 7 and then multiply that answer by 7 to find 7 to the power of 3.
