Question
Raju obtained 75 and 85 marks in mathematics and physics, respectively. Find the marks he must get in chemistry to have an average of 80 marks in all the three subjects.
The correct answer is
80
To find the marks Raju must obtain in chemistry to achieve an average of 80 marks across three subjects (mathematics, physics, chemistry), we need to calculate the total marks he should have and then solve for the chemistry marks.
- Raju's marks in mathematics are 75, and in physics, they are 85.
- We are tasked to find the chemistry marks, denoted as x.
- To have an average of 80 marks in all three subjects, the total marks for the three subjects should be:
\text{Average} = \frac{\text{Total Marks}}{\text{Number of Subjects}}
- Plug in the known values:
80 = \frac{75 + 85 + x}{3}
- To find the total required marks, multiply both sides by 3:
240 = 75 + 85 + x
- Calculate the total of mathematics and physics marks:
75 + 85 = 160
- Replace the sum and solve for x:
240 = 160 + x
- Subtract 160 from both sides:
x = 240 - 160 = 80
- Therefore, Raju must score 80 in chemistry to have an average of 80.
Thus, the correct answer is 80.
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Important Questions from Average (Notes)
- If the average of p numbers is $q^2$ and that of q numbers is $p^2$, then the average of (p + q) numbers is :
- The average of 101 consecutive odd numbers is 303. Find the largest number.
- For three consecutive years, the cost of a product were Rs. $134$ per litre, Rs.$268$ per litre and Rs.$335$ per litre respectively. If a common man spends an average of Rs. $14740$ per year on that product, then what is the average cost of that product per litre for the three years? (In Rs. - upto two decimals)
- If the average of six consecutive even numbers is 13, then the average of the next three even numbers is:
- Raju obtained 75 and 85 marks in mathematics and physics, respectively. Find the marks he must get in chemistry to have an average of 80 marks in all the three subjects.
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