Answer:
5. To find the time in which the loan of N3,900 at the rate of 5% yields N585, we can use the formula for simple interest:
I = P * r * t
where I is the interest, P is the principal (the amount borrowed), r is the interest rate (as a decimal), and t is the time (in years).
Plugging in the given values, we get:
585 = 3900 * 0.05 * t
Solving for t, we get:
t = 3 years
Therefore, it will take 3 years for the loan to yield N585 in interest.
6. To find the time it will take for the simple interest on N70,000 at the rate of 7% to be N20,000, we can again use the formula for simple interest:
I = P * r * t
Plugging in the given values, we get:
20000 = 70000 * 0.07 * t
Solving for t, we get:
t = 4 years
Therefore, it will take 4 years for the simple interest on N70,000 at the rate of 7% to be N20,000.
7. To find the time it takes for N300 to amount to N390 at the rate of 3%, we can use the formula for compound interest:
A = P * (1 + r/n)^(n*t)
where A is the final amount, P is the principal (the initial amount), r is the interest rate (as a decimal), n is the number of times the interest is compounded per year, and t is the time (in years).
Plugging in the given values, we get:
390 = 300 * (1 + 0.03/1)^(1*t)
Simplifying, we get:
1.3^t = 1.3
Taking the logarithm of both sides, we get:
t = log(1.3) / log(1.3)
t ≈ 1.82
Therefore, it takes approximately 1.82 years for N300 to amount to N390 at the rate of 3%.
8. To find the rate percent per annum for a simple interest of N80 on N5600 in 1 year, we can use the formula for simple interest:
I = P * r * t
Plugging in the given values, we get:
80 = 5600 * r * 1
Solving for r, we get:
r = 0.0143 or 1.43%
Therefore, the rate percent per annum is 1.43%.
9. To find the year in which N5100 will yield an interest of N170 at the rate of 2 1/2 per annum, we can use the formula for simple interest:
I = P * r * t
Plugging in the given values, we get:
170 = 5100 * 0.025 * t
Solving for t, we get:
t = 2/3 years
Since the question asks for the year, we need to add 2/3 years to the current year. Assuming the current year is 2021, we get:
2021 + 2/3 ≈ 2022.67
Therefore, N5100 will yield an interest of N170 at the rate of 2 1/2 per annum in the year 2022.
10. To find the rate per annum at which N4,600 will yield an interest of N230 for 2 years, we can again use the formula for simple interest:
I = P * r * t
Plugging in the given values, we get:
230 = 4600 * r * 2
Solving for r, we get:
r = 0.025 or 2.5%
Therefore, the rate per annum is 2.5%.
11. To find the time it takes for N8100 to yield an interest of N729 at the rate of 9% per annum, we can use the formula for simple interest:
I = P * r * t
Plugging in the given values, we get:
729 = 8100 * 0.09 * t
Solving for t, we get:
t = 1 year
Therefore, it takes 1 year for N8100 to yield an interest of N729 at the rate of 9% per annum.
12. To find the rate of interest per annum for an interest of N23 on N2300 for 2 years, we can use the formula for simple interest:
I = P * r * t
Plugging in the given values, we get:
23 = 2300 * r * 2
Solving for r, we get:
r = 0.005 or 0.5%
Therefore, the rate of interest per annum is 0.5%.