I MetroPCS 912 PM myopenmathcom myopenMath Home MATH 082 F
Solution
1) Here given, there are 102 people in that consert.
Let, x and y be the number of adults and children.
Then, x + y = 102.................(i)
Also given, tickets for adults cost $3 while tickets for children cost $2 and total receipt for that concert was $257.
Therefore, 3x + 2y = 257........................(ii)
Now, to solve this equations, we first multiply (i) by 2 and then substract from (ii), we get,
(3x + 2y) - (2x + 2y) = 257 - 204
i.e., x = 53
Putting this value in (i) we get, y = 49
Hence the number of adults is 53 and the number of children is 49.
2) Let, $A be invested in the account paying 5% annual interest.
Since, Ngoc invests a total of $31,000 in two accounts.
Therefore, $(31,000 - A) is invested in the account paying 4% annual interest.
Here given, after 1 year, Ngoc will get the total interest of $1,420.
Therefore, [(A*5*1)/100] + [(31000 - A)*4*1/100] = 1420
i.e., [(5*A) + (31000 - A)*4] / 100 = 1420
i.e., [(5*A) + 124000 - (4*A)] = 142000
i.e., A + 124000 = 142000
i.e., A = 142000 - 124000
i.e., A = 18000
This implies Ngoc invests $18,000 in the account paying 5% annual interest and $(31,000 - 18,000) ,i.e., $13,000 in the account paying 4% annual interest.
