Answer:
The weight of the 8th plant is 39lb
Step-by-step explanation:
Given:
Average Weight of 7 plants = 23lb
Average Weight of 8 plants = 25lb
Required:
Weight of the 8th plant
To solve this, the total weight of the initial 7 plants need to be calculated;
[tex]Average = \frac{Sum-of-weights}{Number-of-Plants}[/tex]
Substitute 23 for Average and 7 for Number of plants
[tex]23 = \frac{Sum-of-weights}{7}[/tex]
Multiply both sides by 7
[tex]7 * 23 = \frac{Sum-of-weights}{7} * 7[/tex]
[tex]161 = Sum-of-weights[/tex]
Hence, the 7 plants weigh 161
Represent the weight of the 8th plant with E
When the 8th plant is added;
The sum of the weight becomes 161 + E
And the number of plants becomes 8
The average is calculated as thus
[tex]Average = \frac{Sum-of-weights}{Number-of-Plants}[/tex]
[tex]25 = \frac{161 + E}{8}[/tex]
Multiply both sides by 8
[tex]8 * 25 = \frac{161 + E}{8} * 8[/tex]
[tex]200 = 161 + E[/tex]
Subtract 161 from both sides
[tex]200 -161 = 161 - 161 + E[/tex]
[tex]39 = E[/tex]
Reorder
[tex]E = 39[/tex]
Hence, the weight of the 8th plant is 39lb
