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Let the characteristic strength be defined as that value, below which not more than 50% of the results are expected to fall. Assuming a standard deviation of 4 MPa, the target mean strength (in MPa) to be considered in the mix design of a M25 concrete would be  
  • a)
    18.42
  • b)
    21.00
  • c)
    25.00
  • d)
    31.58
Correct answer is option 'C'. Can you explain this answer?
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Let the characteristic strength be defined as that value, below which ...
For the given condition,
Target mean strength = characteristic strength = 25 MPa 
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Let the characteristic strength be defined as that value, below which ...
Question Analysis:
The question asks us to determine the target mean strength for the mix design of a M25 concrete. We are given that the characteristic strength is defined as the value below which not more than 50% of the results are expected to fall and the standard deviation is 4 MPa. We need to calculate the target mean strength.

Given:
- Standard deviation = 4 MPa

Target Mean Strength Calculation:
To find the target mean strength, we need to consider the characteristic strength, which is the value below which not more than 50% of the results are expected to fall. In other words, the characteristic strength represents the strength at which we can expect half of the test results to be higher and half to be lower.

Since the target mean strength defines the average strength of the concrete mix, it should be higher than the characteristic strength to ensure that a sufficient number of test results meet the required strength.

Steps to Calculate the Target Mean Strength:

Step 1: Determine the Z-score corresponding to the desired percentage of test results falling below the characteristic strength.
- Given that not more than 50% of the results are expected to fall below the characteristic strength, the desired percentage is 50%.
- The Z-score corresponding to a desired percentage can be determined using a standard normal distribution table.
- For a desired percentage of 50%, the Z-score is 0.

Step 2: Calculate the target mean strength using the formula:
Target Mean Strength = Characteristic Strength + (Z-score * Standard Deviation)

Calculation:
We are given the standard deviation as 4 MPa and the Z-score as 0 (since not more than 50% of the results are expected to fall below the characteristic strength).

Target Mean Strength = Characteristic Strength + (Z-score * Standard Deviation)
Target Mean Strength = Characteristic Strength + (0 * 4)
Target Mean Strength = Characteristic Strength

Therefore, the target mean strength is equal to the characteristic strength.

Conclusion:
Based on the information provided, the target mean strength for the mix design of a M25 concrete is equal to the characteristic strength. Therefore, the correct answer is option 'C' (25.00 MPa).
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Let the characteristic strength be defined as that value, below which ...
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Let the characteristic strength be defined as that value, below which not more than 50% of the results are expected to fall. Assuming a standard deviation of 4 MPa, the target mean strength (in MPa) to be considered in the mix design of a M25 concrete would be a)18.42b)21.00c)25.00d)31.58Correct answer is option 'C'. Can you explain this answer?
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Let the characteristic strength be defined as that value, below which not more than 50% of the results are expected to fall. Assuming a standard deviation of 4 MPa, the target mean strength (in MPa) to be considered in the mix design of a M25 concrete would be a)18.42b)21.00c)25.00d)31.58Correct answer is option 'C'. Can you explain this answer? for Civil Engineering (CE) 2024 is part of Civil Engineering (CE) preparation. The Question and answers have been prepared according to the Civil Engineering (CE) exam syllabus. Information about Let the characteristic strength be defined as that value, below which not more than 50% of the results are expected to fall. Assuming a standard deviation of 4 MPa, the target mean strength (in MPa) to be considered in the mix design of a M25 concrete would be a)18.42b)21.00c)25.00d)31.58Correct answer is option 'C'. Can you explain this answer? covers all topics & solutions for Civil Engineering (CE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Let the characteristic strength be defined as that value, below which not more than 50% of the results are expected to fall. Assuming a standard deviation of 4 MPa, the target mean strength (in MPa) to be considered in the mix design of a M25 concrete would be a)18.42b)21.00c)25.00d)31.58Correct answer is option 'C'. Can you explain this answer?.
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