Examples with solutions for Averages for 5th Grade: Determining the average without calculation

Exercise #1

Without calculating, choose the average of the following group of numbers:

33,38,49,45,40 33,38,49,45,40

Video Solution

Step-by-Step Solution

To find the average of the numbers 33,38,49,45,4033, 38, 49, 45, 40 without calculating directly, we can roughly estimate it by identifying a central value.

Step 1: Arrange the numbers for clarity: 33,38,40,45,4933, 38, 40, 45, 49.

Step 2: Observe that these numbers range from 3333 to 4949, with 4040 being the middle value.

The numbers 38,40,4538, 40, 45 are tightly centered around 4040, suggesting that the average would be closer to 4040.

Step 3: Evaluate the closest given choices. The choice of 4141 aligns closely with our estimation, just slightly above 4040 due to the higher numbers 4545 and 4949. This suggests a slight increase around the middle.

Therefore, the approximate average of the numbers is 4141.

Answer

41

Exercise #2

Without calculating, choose the average of the following group of numbers:

133,106,176,126,199 133,106,176,126,199

Video Solution

Step-by-Step Solution

To solve this problem, we'll visually estimate a balance of the numbers provided:

  1. First, identifying the extremities: - The lowest number is 106 106 - The highest number is 199 199 .
  2. The middle range involves 126 126 , 133 133 , and 176 176 , which cluster around 148 148 .
  3. Although 199 199 and 106 106 stretch the average, 133 133 and 126 126 counteract 176 176 's high point.
  4. Thus, balancing these extremities by approximating allows 148 148 to emerge as a logical middle value.
  5. Therefore, the estimated average that best represents the centrality of these numbers is 148 148 .

Accordingly, we choose 148 as the best estimate for the average, which is represented by Choice 3: 148 148 .

Answer

148

Exercise #3

Without calculating, choose the average of the following group of numbers:

10,80,96,84,95 10,80,96,84,95

Video Solution

Step-by-Step Solution

To solve this problem, let's first quickly glance at the numbers given: 10,80,96,84,9510, 80, 96, 84, 95.

Since calculating the precise average is not required, we can estimate by observing:

  • One number is relatively small: 1010.
  • The other numbers, 80,96,84,9580, 96, 84, 95, are all fairly close to each other and significantly larger than 1010, indicating that the average will lean towards the higher values.

Examining the choices, which are 11,9,73,9711, 9, 73, 97:

  • 7373 is a choice that logically fits between the smallest and largest numbers in our list.
  • 11,911, 9, and 9797 appear to be far from typical average values given the numbers provided.

As 7373 is nearer to the typical values seen in the majority of the list, \textbf{73} would be the most reasonable choice for the average.

Therefore, without full computation, the most sensible choice for the average of these numbers is 73\textbf{73}.

Answer

73

Exercise #4

Without calculating, choose the average of the following group of numbers:

11,8,14,20,7 11,8,14,20,7

Video Solution

Step-by-Step Solution

To solve this problem, we'll employ reasonable estimation and logic:

  • Step 1: Identify the range of numbers, which is from 7 to 20.
  • Step 2: Consider that the average (mean) is typically near the middle of the list when the numbers are evenly distributed.
  • Step 3: Identify the number configuration: 7,8,11,14,20 7, 8, 11, 14, 20 . Notice 11 11 is close to the middle, but 20 20 as an outlier pulls the average higher.

Reviewing the numbers:

  • 11 and 14 are central, flanked by 8 and 7 on the lower side, and 20 on the upper side.
  • Hence, guess an average slightly above the median (11).

Since we're not calculating, a reasonable average looking at the numbers and distribution is 12 12 .

The solution to the problem is thus 12 12 .

Answer

12

Exercise #5

Without calculating, choose the number that cannot be the average of the following group of numbers:

10,11,12,13,14 10,11,12,13,14

Video Solution

Step-by-Step Solution

To solve this problem, let us examine the range of the numbers given:

The smallest number in the set is 10 10 , and the largest is 14 14 . Hence, any average of these numbers must fall within this range, i.e., between 10 and 14.

Considering the choices:

  • 12 12 is within the range 10 10 to 14 14 .
  • 9 9 is outside of this range.
  • 13 13 is within the range 10 10 to 14 14 .
  • 11 11 is within the range 10 10 to 14 14 .

Thus, it is clear that the number that cannot be the average of (10,11,12,13,14)(10, 11, 12, 13, 14) is 9 9 , as it does not lie within the required range.

Answer

9

Exercise #6

Which answer cannot be the average of the group of numbers below?

8,7,5,10 8,7,5,10

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these steps:

  • Step 1: Calculate the sum of the numbers.
  • Step 2: Find the average by dividing this sum by the number of numbers.
  • Step 3: Compare this calculated average to the given options to identify which cannot be the average.

Now, let's work through each step:
Step 1: Calculate the sum of the numbers: 8+7+5+10=308 + 7 + 5 + 10 = 30.
Step 2: Find the average by dividing the sum by the total number of numbers: 304=7.5\frac{30}{4} = 7.5.
Step 3: Compare the calculated average to the options provided:

  • Option 1: 66 - not equal to 7.57.5.
  • Option 2: 88 - not equal to 7.57.5, but close enough to an integer comparison standard.
  • Option 3: 1212 - clearly not possible since 7.5<127.5 < 12.
  • Option 4: 99 - not equal to 7.57.5.

Of all these options, the choice that cannot possibly be the average based on the numbers given is 1212. Therefore, the answer is 1212.

Answer

12