\(\mathrm{m(t) = -0.0274(t/7)^2 + 7.3873(t/7) + 75.032}\)The function m gives the predicted body mass \(\mathrm{m(t)}\), in kilograms (kg), of a...
GMAT Advanced Math : (Adv_Math) Questions
\(\mathrm{m(t) = -0.0274(t/7)^2 + 7.3873(t/7) + 75.032}\)
The function m gives the predicted body mass \(\mathrm{m(t)}\), in kilograms (kg), of a certain animal t days after it was born in a wildlife reserve, where \(\mathrm{t \leq 330}\). Which of the following is the best interpretation of the statement '\(\mathrm{m(330)}\) is approximately equal to 362' in this context?
The predicted body mass of the animal was approximately \(\mathrm{330\text{ kg}}\) \(\mathrm{362\text{ days}}\) after it was born.
The predicted body mass of the animal was approximately \(\mathrm{362\text{ kg}}\) \(\mathrm{330\text{ days}}\) after it was born.
The predicted body mass of the animal was approximately \(\mathrm{362\text{ kg}}\) \(\mathrm{\frac{330}{7}\text{ days}}\) after it was born.
The predicted body mass of the animal was approximately \(\mathrm{\frac{330}{7}\text{ kg}}\) \(\mathrm{362\text{ days}}\) after it was born.
1. TRANSLATE the mathematical statement
- Given: "m(330) is approximately equal to 362"
- This means: \(\mathrm{m(330) = 362}\)
- What this tells us:
- 330 is the input value (what goes into the function)
- 362 is the output value (what comes out of the function)
2. INFER what the input and output represent
- From the function definition:
- \(\mathrm{m(t)}\) = predicted body mass in kilograms
- \(\mathrm{t}\) = days after the animal was born
- Therefore:
- Input 330 = 330 days after birth
- Output 362 = 362 kg of predicted body mass
3. TRANSLATE back to English
- Put it together: "The predicted body mass of the animal was approximately 362 kg 330 days after it was born"
- This matches choice B exactly
Answer: B
Why Students Usually Falter on This Problem
Most Common Error Path:
Poor TRANSLATE reasoning: Students mix up which number represents the input versus the output in function notation. They might think that since 330 appears first in \(\mathrm{m(330) = 362}\), it should also come first when describing the mass, leading them to say "330 kg" instead of recognizing that 330 is the time input.
This may lead them to select Choice A (330 kg at 362 days).
Second Most Common Error:
Weak INFER skill: Students see the \(\mathrm{(t/7)}\) terms in the function and mistakenly think they need to convert 330 to weeks by dividing by 7, not realizing that t is already defined as days and the function handles any necessary conversions internally.
This may lead them to select Choice C (362 kg at 330/7 days).
The Bottom Line:
Function interpretation problems require careful attention to what goes in (input) versus what comes out (output), combined with understanding the real-world meaning of each variable. The mathematical notation tells you the relationship, but you must translate it correctly to English.
The predicted body mass of the animal was approximately \(\mathrm{330\text{ kg}}\) \(\mathrm{362\text{ days}}\) after it was born.
The predicted body mass of the animal was approximately \(\mathrm{362\text{ kg}}\) \(\mathrm{330\text{ days}}\) after it was born.
The predicted body mass of the animal was approximately \(\mathrm{362\text{ kg}}\) \(\mathrm{\frac{330}{7}\text{ days}}\) after it was born.
The predicted body mass of the animal was approximately \(\mathrm{\frac{330}{7}\text{ kg}}\) \(\mathrm{362\text{ days}}\) after it was born.