Question

Сколь­ко досок дли­ной 3,5 м, ши­ри­ной 20 см и тол­щи­ной 20 мм вый­дет из че­ты­рех­уголь­ной балки дли­ной 105 дм, име­ю­щей в се­че­нии пря­мо­уголь­ник раз­ме­ром 30 см 40 см?

Answer 1

Находим объём бруска : 1050 см * 40 см * 30 см = 1260000 см кв.
теперь находим объём доски : 350 см * 20 см * 2 см = 14000 см кв

1260000/14000 = 90 досок 

Answer 2

Calculating the Number of Planks

To calculate the number of planks that can be obtained from the given rectangular beam, we can use the following formula:

Number of planks = (Total length of beam) / (Length of each plank)

Given: - Length of each plank = 3.5 m - Width of each plank = 20 cm - Thickness of each plank = 20 mm - Total length of the beam = 105 dm - Cross-section of the beam is a rectangle with dimensions 30 cm x 40 cm

Using the formula, we can calculate the number of planks that can be obtained from the beam.

Calculation

First, we need to convert all measurements to the same unit for consistency. Let's convert the total length of the beam from decimeters to meters: - 105 dm = 10.5 m

Now, we can calculate the number of planks using the formula: - Number of planks = (10.5 m) / (3.5 m) = 3 planks

Conclusion

Therefore, from the given rectangular beam, a total of 3 planks can be obtained, each with a length of 3.5 m, a width of 20 cm, and a thickness of 20 mm.