Answer:
5
Step-by-step explanation:
Given:
1 inch : 18 kilometers
Let us use the ratio and proportion method:
a:b = c:d where ad = bc
0.8 inches is <u>14.4 kilometers</u>
1 : 18 = 0.8 : x
x = 0.8 * 18
x = 14.4 km
1.4 inches is <u>25.2 kilometers</u>
1: 18 = 1.4 : x
x = 18 * 1.4
x = 25.2 km
2.1 inches is <u>37.8 kilometers</u>
1 : 18 = 2.1 : x
x = 18 * 2.1
x = 37.8 km
1. A, It goes past the 4, but the circle is not shaded because the answer cannot be 4
2. C. It goes below the 11 and is shaded because it can be equal to 11
3. D. It is less than 13 and cannot equal thirteen, hence the non shaded circle
4. B. I goes past the -2 and has the circle shaded because it can be equal to the -2
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.
_____
The above can be written down from your knowledge of binary sequences. If you want a more formal development, read on.
__
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
<span>π </span>* 6 = 18.8495559215 / 4 = 4.71238898038
