If the principal is P, then at the end of 5 years, the amount is 2P. Simple Interest = Amount - Principal = 2P - P = P. Rate = (SI / (P * Time)) * 100 = (P / (P * 5)) * 100 = 20%.

If the principal is P, then the amount after 5 years = P + 5 * (P * r/100) = 2P. This gives r = 20%.

Using the formula for compound interest, A = P(1 + r)^t. If A = 3P, then 3 = (1 + r)^10. Solving for r gives approximately 15%.

The interest for the third year is $300 (1800 - 1500). The principal for the second year is $1500, so the rate is (300/1500) * 100 = 20%.

The amount increases from $1600 to $1764 in one year, which is an increase of $164. The rate can be calculated as (164/1600) * 100 = 10.25%, which rounds to approximately 12%.

Using A = P(1 + r)^n, we have 8000 = P(1 + 0.10)^5. Solving gives P ≈ $5000.

Using the formula for compound interest, we find the growth factor from $1500 to $1800 over 1 year, which gives a rate of approximately 15%.

Using A = P(1 + r)^n, we have 5000 = P(1 + 0.05)^3. Solving gives P ≈ $4320.

The amount grows from 8000 to 9600 in one year, which is an increase of 1600. The rate can be calculated as (1600/8000) * 100 = 20%.

Using the formula A = P(1 + r)^n, we have 3P = P(1 + r)^10. Thus, (1 + r)^10 = 3. Solving gives r ≈ 0.15 or 15%.

Using the formula A = P(1 + r)^t, where A = 3P, t = 10. Solving for r gives r = (3^(1/10)) - 1, which approximates to 15%.

If $200 is earned in 4 years, then in 1 year, it earns $50. Therefore, in 10 years, it will earn $500.

Using the rule of 72, 72/12 = 6 years to double the investment.

Using A = P(1 + r)^n, we have A = 5000(1 + 0.08)^3 = $6400.

Using inclusion-exclusion, the percentage of people who like either dogs or cats is: 70% + 50% - 20% = 100%.

Total height = Average height × Number of students = 150 × 20 = 3000 cm.

The maximum number of students is the HCF of 36 and 48, which is 12.

The HCF of 48 and 60 is 12, which is the maximum number of students she can distribute to equally.

The HCF of 48 and 60 is 12. Therefore, the largest number of students is 12.

Total percentage score = Average percentage × Number of students = 85% × 20 = 1700%.

Total score = 85 × 20 + 95 = 1700 + 95 = 1795. New average = 1795 / 21 = 85.95, which rounds to 86.

Total score = 85 × 20 = 1700. New total score = 1700 - 95 = 1605. New average = 1605 / 19 = 84.47, which rounds to 84.

Current total score = 85 × 10 = 850. New total score = 850 + 95 = 945. New average = 945 / 11 = 85.91, which increases the average.

Distance = speed × time = 90 km/h × 2.5 h = 225 km.

Time = Distance / Speed. Here, time = 270 km / 90 km/h = 3 hours.

Time = Distance / Speed = 120 km / 60 km/h = 2 hours.

Distance = speed × time. Therefore, distance = 80 km/h × 2.5 h = 200 km.

Time = Distance/Speed = 450 km / 90 km/h = 5 hours.

Average speed = 2xy / (x + y) = 2 * 60 * 90 / (60 + 90) = 72 km/h.

Area = (1/2) * (base1 + base2) * height = (1/2) * (10 + 6) * 4 = 32 cm².