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Read the statements carefully and select...

Read the statements carefully and select the correct option.
Statement-I : A rectangular tank is 80 m long and 25 m broad. Water flows into it through a pipe whose cross-section is `25" cm"^2`, at the rate of 16 km per hour. The rise in the level of water in the tank in 45 minutes is 2.5 cm.
Statement-II : If V is the volume of cuboid of dimensions a, b and c and A is its surface area, then `(A)/(V) =2 [a + b+c]`.

A

Statement-I is true but Statement-II is false.

B

Statement-I is false but Statement-II is true.

C

Both Statement-I and Statement-II are true.

D

Both Statement-I and Statement-II are false.

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we will analyze both statements and determine their validity step by step. ### Step 1: Analyze Statement I We have a rectangular tank with the following dimensions: - Length (L) = 80 m - Breadth (B) = 25 m Water flows into the tank through a pipe with a cross-sectional area of 25 cm² at a rate of 16 km/h. We need to find out if the rise in water level in 45 minutes is indeed 2.5 cm. #### Step 1.1: Convert units First, convert the cross-sectional area of the pipe from cm² to m²: - 25 cm² = 25 / 10000 m² = 0.0025 m² Next, convert the flow rate from km/h to m/s: - 16 km/h = (16 * 1000) / (60 * 60) m/s = 4.44 m/s #### Step 1.2: Calculate the volume of water flowing into the tank Now, calculate the volume of water that flows into the tank in 45 minutes: - Time in seconds = 45 minutes * 60 seconds/minute = 2700 seconds - Volume of water (V) = Flow rate (in m/s) * Cross-sectional area (in m²) * Time (in seconds) - V = 4.44 m/s * 0.0025 m² * 2700 s = 30 m³ #### Step 1.3: Calculate the rise in water level Now, we need to calculate the rise in water level in the tank: - Volume of water = Length * Breadth * Height of water rise - 30 m³ = 80 m * 25 m * Height - Height = 30 m³ / (80 m * 25 m) = 30 / 2000 = 0.015 m = 1.5 cm Since the calculated rise in water level (1.5 cm) is not equal to the stated rise (2.5 cm), Statement I is **incorrect**. ### Step 2: Analyze Statement II Statement II states that if V is the volume of a cuboid with dimensions a, b, and c, and A is its surface area, then \( \frac{A}{V} = 2(a + b + c) \). #### Step 2.1: Write the formulas - Volume (V) = a * b * c - Surface Area (A) = 2(ab + ac + bc) #### Step 2.2: Calculate \( \frac{A}{V} \) Now, we calculate \( \frac{A}{V} \): - \( \frac{A}{V} = \frac{2(ab + ac + bc)}{abc} \) #### Step 2.3: Simplify the expression This simplifies to: - \( \frac{A}{V} = 2 \left( \frac{ab + ac + bc}{abc} \right) = 2 \left( \frac{1}{c} + \frac{1}{b} + \frac{1}{a} \right) \) This does not equal \( 2(a + b + c) \). Therefore, Statement II is also **incorrect**. ### Conclusion Both Statement I and Statement II are incorrect. ### Final Answer Both statements are false.
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