Question

The mean length of 7 planks of wood is 1.35m. When an extra plank of wood is added, the mean length of a plank of wood increase to 1.4m. the length of the extra plank of wood that was added is Select one a. 2. 4 b. 1 C. 1.25 d. 1.75V​

Answer 1

Answer: Hello There!................

Mean = Sum of observation / total number of observation

Mean = 1.35m

1.35  = Sum of length of 7 wood planks/ 7

1.35*7 = Sum of the length of 7 wood planks

9.45 = Sum of the length of 7 wood planks

Let the length of extra added wood plank = x

So,

(Sum of the length of 7 wood planks + x) / 8 = 1.4m

(9.45 + x) / 8 = 1.4

9.45 + x = 1.4 * 8

9.45 + x = 11.2

x = 11.2- 9.45

= 1.75

So,

The length of extra added wood plank = 1.75m

Step-by-step explanation:

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