900
700
1000
800
Nitu's initial capital is ₹20,000. She allocates her funds as follows:
The total annual interest earned across all investments is ₹1,000, equivalent to 5% of her initial ₹20,000. Determine the interest rate \( x \) for Bank C and calculate the interest Nitu would earn if the entire ₹20,000 were invested in Bank C at this rate.
The interest earned from Bank A is calculated as:
\[ \text{Interest from Bank A} = \frac{8000 \times 5.5 \times 1}{100} = ₹440 \]
The interest earned from Bank B is calculated as:
\[ \text{Interest from Bank B} = \frac{5000 \times 5.6 \times 1}{100} = ₹280 \]
First, determine the principal amount invested in Bank C:
Remaining principal: \[ P = 20000 - (8000 + 5000) = ₹7000 \]
The interest earned from Bank C is:
\[ \text{Interest from Bank C} = \frac{7000 \times x}{100} = ₹70x \]
The sum of the interest from all three banks equals the total annual interest:
\[ 440 + 280 + 70x = 1000 \]
Simplify the equation:
\[ 720 + 70x = 1000 \]
Isolate the term with \( x \):
\[ 70x = 1000 - 720 \]
\[ 70x = 280 \]
Solve for \( x \):
\[ x = \frac{280}{70} = 4 \]
Therefore, the interest rate at Bank C is \( \boxed{4\%} \).
If Nitu invested the entire ₹20,000 in Bank C at the determined rate of 4%, the interest earned would be:
\[ \text{Interest} = \frac{20000 \times 4}{100} = ₹800 \]
If Nitu had invested her entire ₹20,000 in Bank C at a rate of 4%, her annual interest earnings would be: \[ \boxed{₹800} \]