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- Question
The average of 7 consecutive numbers is 20. The largest of these numbers is :
Options- A. 21
- B. 22
- C. 23
- D. 24
- Correct Answer
- 23
ExplanationLet the numbers be x, x + 1, x + 2, x + 3, x + 4, x + 5 and x + 6,
Then (x + (x + 1) + (x + 2) + (x + 3) + (x + 4) + (x + 5) + (x + 6)) / 7 = 20.
or 7x + 21 = 140 or 7x = 119 or x =17.
Latest number = x + 6 = 23.
- 1. The average weight of a class of 24 students is 35 kg. If the weight of the teacher be included, the average rises by 400 g. The weight of the teacher is :
Options- A. 45 kg
- B. 46 kg
- C. 47 kg
- D. 48 kg Discuss
- 2. The average of five consecutive odd numbers is 61. What is the difference between the highest and lowest numbers :
Options- A. 4
- B. 8
- C. 12
- D. 16 Discuss
- 3. The average weight of 8 persons increases by 2.5 kg when a new person comes in place of one of them weighing 65 kg. What might be the weight of the new person ?
Options- A. 70 kg
- B. 75 kg
- C. 80 kg
- D. 85 kg Discuss
- 4. The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero ?
Options- A. 0
- B. -1
- C. 1
- D. none of these Discuss
- 5. A grocer has a sale of Rs 6435, Rs. 6927, Rs. 6855, Rs. 7230 and Rs. 6562 for 5 consecutive months. How much sale must he have in the sixth month so that he gets an average sale of Rs, 6500 ?
Options- A. 4991
- B. 5467
- C. 5987
- D. 6453 Discuss
- 6. The mean temperature of Monday to Wednesday was 37 degree celsius and of Tuesday to Thursday was 34 degree celsius . If the temperature on Thursday was (4/5) th that of Monday, the temperature on Thursday was?
Options- A. 38 degree celsius
- B. 36 degree celsius
- C. 40 degree celsius
- D. 39 degree celsius Discuss
- 7. After replacing an old member by a new member, it was found that the average age of five members of a club is the same as it was 3 years ago. What is the difference between the ages of the replaced and the new member ?
Options- A. 12
- B. 13
- C. 14
- D. 15 Discuss
- 8. A pupil's marks were wrongly entered as 83 instead of 63. Due to that the average marks for the class got increased by half. The number of pupils in the class is :
Options- A. 45
- B. 40
- C. 39
- D. 37 Discuss
- 9. The mean of 50 observations was 36. It was found later that an observation 48 was wrongly taken as 23. The corrected new mean is :
Options- A. 35
- B. 36.5
- C. 40
- D. 42 Discuss
- 10. Of the four numbers, whose average is 60, the first is one-fourth of the sum of the last three. The first number is :
Options- A. 17
- B. 29
- C. 36
- D. 48 Discuss
Average problems
Search Results
Correct Answer: 45 kg
Explanation:
Weight of the teacher = (35.4 x 25 - 35 x 24) kg = 45 kg.
Correct Answer: 8
Explanation:
Let the numbers be x, x + 2, x + 4, x + 6 and x + 8.
Then [x + (x + 2) + (x + 4) + (x + 6) + (x + 8) ] / 5 = 61.
or 5x + 20 = 305 or x = 57.
So, required difference = (57 + 8) - 57 = 8
Correct Answer: 85 kg
Explanation:
Total weight increased = (8 x 2.5) kg = 20 kg.
Weight of new person = (65 + 20) kg = 85 kg.
Correct Answer: 0
Explanation:
Average of 20 numbers = 0.
Sum of 20 numbers = (0 * 20) = 0.
It is quite possible that 19 of these numbers may be positive and if their sum is a, then 20th number is (- a).
Correct Answer: 4991
Explanation:
Total sale for 5 months = Rs. (6435 + 6927 + 6855 + 7230 + 6562) = Rs. 34009.
Required sale = Rs.[(6500 x 6) - 34009]
= Rs. (39000 - 34009)
= Rs. 4991.
Correct Answer: 36 degree celsius
Explanation:
Let, temperature of Monday = a Temperature of Tuesday = b Temperature of Wednesday = c Temperature of Thursday = 4a/5 Sum of temperatures of Monday to Wednesday = 3×37 = 111 => a+b+c=111------(1) Sum of temperatures of Tuesday to Thursday = 3×34 = 102 b+c+(4a/5) = 102 ------(2) (1)-(2)=> a−(4a/5)=111−102 a/5=9 a=45 Temperature on Thursday = 4a/5 =4×45/5 =36
Correct Answer: 15
Explanation:
i) Let the ages of the five members at present be a, b, c, d & e years.
And the age of the new member be f years.
ii) So the new average of five members' age = (a + b + c + d + f)/5 ------- (1)
iii) Their corresponding ages 3 years ago = (a-3), (b-3), (c-3), (d-3) & (e-3) years
So their average age 3 years ago = (a + b + c + d + e - 15)/5 = x ----- (2)
==> a + b + c + d + e = 5x + 15
==> a + b + c + d = 5x + 15 - e ------ (3)
iv) Substituting this value of a + b + c + d = 5x + 15 - e in (1) above,
The new average is: (5x + 15 - e + f)/5
Equating this to the average age of x years, 3 yrs, ago as in (2) above,
(5x + 15 - e + f)/5 = x
==> (5x + 15 - e + f) = 5x
Solving e - f = 15 years.
Thus the difference of ages between replaced and new member = 15 years.
Correct Answer: 40
Explanation:
Let there be x pupils in the class.
Total increase in marks = (x * 1/2) = x/2.
x/2 = (83 - 63) => x/2 = 20 => x = 40.
Correct Answer: 36.5
Explanation:
Correct Sum = (36 * 50 + 48 - 23) = 1825.
Correct mean = = 1825/50 = 36.5
Correct Answer: 48
Explanation:
Let the first number be x,
Then, sum of the four numbers = x + 4x = 5x.
so, 5x/4 = 60 or x = (60 * 4) / 5 = 48.
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