A rectangular box of the dimensions 4 x 2 x 2 units is to be tied up with a ribbon lengthwise and

breadthwise only once. For the knot, an additional 4 units of ribbon-length is required. What is
the number of minimum units of ribbon-length required for this activity ?

make a diagram and draw in your ribbons,

add them up , then add 4 units for tying.

A slightly more difficult version of your question was answered by Steve here

http://www.jiskha.com/display.cgi?id=1448268926

16

Correct! The ribbon needs to go around the box twice, once lengthwise and once breadthwise. The length of the box is 4 units and the breadth of the box is 2 units, so the total length of ribbon needed for both is 2(4 + 2) = 12 units. Adding the 4 units for tying the knot gives a total of 12 + 4 = 16 units.

To find the minimum units of ribbon-length required for tying up the rectangular box, we need to calculate the perimeter of the box and add 4 units to account for the knot.

The perimeter of a rectangular box is calculated by adding the lengths of all four sides. In this case, since we are tying up the box lengthwise and breadthwise, the sides we need to consider are the length (4 units) and the breadth (2 units). The height (2 units) is not relevant for the knot.

Therefore, the perimeter of the rectangular box is calculated as follows:
Perimeter = 2 * (length + breadth)
= 2 * (4 + 2)
= 2 * 6
= 12 units

Now, we add the additional 4 units required for the knot:
Minimum units of ribbon-length = Perimeter + 4
= 12 + 4
= 16 units

Thus, the minimum units of ribbon-length required for this activity is 16 units.