We are given that a bag contains 15 potatoes with a mean mass of 136g. Then 3 more potatoes, each with a mean mass of 130g, are added to the bag. We need to calculate the mean mass of all the potatoes in the bag.

1. Problem Description

We are given that a bag contains 15 potatoes with a mean mass of 136g. Then 3 more potatoes, each with a mean mass of 130g, are added to the bag. We need to calculate the mean mass of all the potatoes in the bag.

2. Solution Steps

First, we calculate the total mass of the initial 15 potatoes.

$Total\,mass\,of\,15\,potatoes = Number\,of\,potatoes \times Mean\,mass$

$Total\,mass\,of\,15\,potatoes = 15 \times 136 = 2040\,g$

Next, we calculate the total mass of the 3 potatoes added.

$Total\,mass\,of\,3\,potatoes = Number\,of\,potatoes \times Mean\,mass$

$Total\,mass\,of\,3\,potatoes = 3 \times 130 = 390\,g$

Then, we calculate the total mass of all the potatoes.

$Total\,mass\,of\,all\,potatoes = Total\,mass\,of\,15\,potatoes + Total\,mass\,of\,3\,potatoes$

$Total\,mass\,of\,all\,potatoes = 2040 + 390 = 2430\,g$

Now, we calculate the total number of potatoes.

$Total\,number\,of\,potatoes = 15 + 3 = 18$

Finally, we calculate the mean mass of all the potatoes.

$Mean\,mass\,of\,all\,potatoes = \frac{Total\,mass\,of\,all\,potatoes}{Total\,number\,of\,potatoes}$

$Mean\,mass\,of\,all\,potatoes = \frac{2430}{18} = 135\,g$

3. Final Answer

The mean mass of all the potatoes in the bag is 135 g.