Andre has a summer job selling magazine subscriptions he earned $25 per week plus $3 for every subscription he sells.Andre hopes
1 answer:
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48. The surface area of a cylinder is given by
... A = 2πr² + 2πrh = 2πr(r+h)
For r = 13 mi and h = 7 mi, this becomes
... A = 2π(13 mi)(13 mi + 7 mi) = 520π mi²
The surface area of the cylinder is 520π mi² ≈ 1634 mi².
49. The surface area of a rectangular prism is
... A = 2(LW + H(L+W))
For L = 20 m, W = 10 m, H = 7 m, this becomes
... A = 2((20 m)(10 m) + (7 m)(20 m + 10 m)) = 2(200 m² + 210 m²) = 820 m²
The surface area of the prism is 820 m².
50. The formula is the same as for problem 48.
For r = 10 m and h = 13 m, this becomes
... A = 2π(10 m)(10 m + 13 m) = 460π m² ≈ 1445 m²
The surface area of the cylinder is 460π m² ≈ 1445 m².
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When calculations are repetitive, it is convenient to let a calculator or spreadsheet do them.
Answer:
x=-4
Step-by-step explanation:
Given that the jeweler has alloys that are 25% gold, 50% gold, and 82% gold.
As he wants to make 14 grams of an alloy by adding two different alloys that is precisely 75% gold, so one alloy must have a percentage of gold more than 75%.
One alloy is 82% gold and, the second can be chosen between 25% gold, 50% gold, so there are two cases.
Case 1: 82% gold + 50% gold
Let x grams of 82% gold and y grams of 50% gold added to make x+y=14 grams of 75% gold, so
75% of 14 = 82% of x + 50% of y
[as x+y=14]
grams
and grams.
Hence, 10.9375 grams of 82% gold and 3.0625 grams of 50% gold added to make 14 grams of 75% gold.
Case 2: 82% gold + 25% gold
Let x grams of 82% gold and y grams of 25% gold added to make x+y=14 grams of 75% gold, so
75% of 14 = 82% of x + 25% of y
grams
and grams.
Hence, 12.28 grams of 82% gold and 1.72 grams of 50% gold added to make 14 grams of 75% gold.