Average
- In an examination the average marks obtained by John in English, Maths, Hindi and Drawing were 50. His average marks in Maths, Science, Social Studies and Craft were 70. If the average marks in all seven subjects is 58, his score in maths was
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Here , The average marks obtained by John in English, Maths, Hindi and Drawing = 50.
Average marks in Maths, Science, Social Studies and Craft = 70
The average marks in all seven subjects = 58
According to question ,
Marks in Maths = 50 × 4 + 70 × 4 – 58 × 7
Marks in Maths = 200 + 280 – 406Correct Option: D
Here , The average marks obtained by John in English, Maths, Hindi and Drawing = 50.
Average marks in Maths, Science, Social Studies and Craft = 70
The average marks in all seven subjects = 58
According to question ,
Marks in Maths = 50 × 4 + 70 × 4 – 58 × 7
Marks in Maths = 200 + 280 – 406
Marks in Maths = 480 – 406 = 74
- The average of 9 numbers is 30. The average of first 5 numbers is 25 and that of the last 3 numbers is 35. What is the 6th number?
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According to question,
The average of 9 numbers = 30
Now,The total of 9 numbers = 30 × 9 = 270
The average of first 5 numbers = 25
∴ The total of first 5 numbers = 25 × 5 = 125
and Total of last 3 numbers = 3 × 35 = 105
Required answer = The total of 9 numbers - ( The total of first 5 numbers + Total of last 3 numbers )Correct Option: C
According to question,
The average of 9 numbers = 30
Now,The total of 9 numbers = 30 × 9 = 270
The average of first 5 numbers = 25
∴ The total of first 5 numbers = 25 × 5 = 125
and Total of last 3 numbers = 3 × 35 = 105
Required answer = The total of 9 numbers - ( The total of first 5 numbers + Total of last 3 numbers )
Hence, required answer = 270 – (125 + 105) = 270 – 230 = 40
- The average temperature for Monday, Tuesday, Wednesday and Thursday was 48° . The average temperature for Tuesday, Wednesday, Thursday and Friday was 52°, If the temperature on Monday was 42°, then the temperature on Friday was (in degrees)
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Given that , The average temperature for Monday, Tuesday, Wednesday and Thursday = 48°
Monday + Tuesday + Wednesday + Thursday = 4 × 48° = 192° ..... (i)
The average temperature for Tuesday, Wednesday, Thursday and Friday = 52°
Tuesday + Wednesday + Thursday + Friday = 4 × 52° = 208° ..... (ii)
By equation (ii) – (i),Correct Option: A
Given that , The average temperature for Monday, Tuesday, Wednesday and Thursday = 48°
Monday + Tuesday + Wednesday + Thursday = 4 × 48° = 192° ..... (i)
The average temperature for Tuesday, Wednesday, Thursday and Friday = 52°
Tuesday + Wednesday + Thursday + Friday = 4 × 52° = 208° ..... (ii)
By equation (ii) – (i),
Friday – Monday = 208° – 192° = 16
⇒ Friday = 16 + 42 = 58°
- The average temperature of the first 4 days of a week was 37°C and that of the last 4 days of the week was 41°C. If the average temperature of the whole week was 39°C, the temperature of the fourth day was
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According to question ,
M + T + W + TH = 4 × 37 = 148°C ........ (i)
TH + F + S + S = 4 × 41 = 164°C ........ (ii)
M + T +....+ S + S = 7 × 39 = 273°C ........ (iii)
∴ The temperature of the fourth day = ( M + T + W + TH ) + ( TH + F + S + S ) - ( M + T +....+ S + S )Correct Option: C
According to question ,
M + T + W + TH = 4 × 37 = 148°C ........ (i)
TH + F + S + S = 4 × 41 = 164°C ........ (ii)
M + T +....+ S + S = 7 × 39 = 273°C ........ (iii)
∴ The temperature of the fourth day = ( M + T + W + TH ) + ( TH + F + S + S ) - ( M + T +....+ S + S )
The temperature of the fourth day = 148 + 164 – 273 = 39°C
- Three numbers are such that the average of first two numbers is 2, the average of the last two numbers is 3 and the average of the first and the last numbers is 4, then the average of three numbers is equal to
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Numbers in order
⇒ a, b and c
According to question ,
∴ a + b = 2 × 2 = 4
b + c = 2 × 3 = 6
c + a = 2 × 4 = 8
On adding,
2 (a + b + c) = 4 + 6 + 8 = 18⇒ a + b + c = 18 = 9 2
Correct Option: C
Numbers in order
⇒ a, b and c
According to question ,
∴ a + b = 2 × 2 = 4
b + c = 2 × 3 = 6
c + a = 2 × 4 = 8
On adding,
2 (a + b + c) = 4 + 6 + 8 = 18⇒ a + b + c = 18 = 9 2 ∴ Required average = 9 = 3 3
