Question 1202277
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Part (a)


x = amount invested at 6%
102000-x = amount invested at 12%


0.06x = simple interest earned at 6% for one year
0.12(102000-x) = simple interest earned at 12% for one year


Add the two subtotals and set the sum equal to 7800. Solve for x.


0.06x+0.12(102000-x) = 7800
0.06x+0.12*102000+0.12*(-x) = 7800
0.06x+12240-0.12x = 7800
-0.06x+12240 = 7800
-0.06x = 7800-12240
-0.06x = -4440
x = -4440/(-0.06)
x = 74000


which leads to
102000-x = 102000-74000 = 28000



Answers:
$74,000 invested at 6%
$28,000 invested at 12%


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Part (b)


The 12% investment is more risky compared to the 6% investment. It's possible the 12% account could go to zero. You would lose all of your money if you put all of your eggs in one basket. It's better to diversify. 
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