Question

the lengths of two bodies measured by a metre scale are l1=(20+-0.5)cm l2=(15+-0.2)cm calculate sum of these lengths difference between the lengths ​

Answer 1

Answer:

1) (20+-0.5)+(15+-0.2)

=(20-0.5)+(15-0.2)

=19.5+14.8

=34.3

2)(20-0.5) - (15-0.2)

=19.5 - 14.8

=4.7

Answer 2

Answer:

sum =  37 cm

difference = 34.3cm

Explanation:

Measurement of Length

Measuring length means measurement of the length of any object with the help of measuring tools like a ruler, measuring tape, etc. For example, the length of a pencil can be measured in inches using a ruler. The height of students in a class can be measured using a feet scale. There are units of length like inches, centimeters, meters, feet, etc.

Tools to Measure Length

There are different tools for the measurement of the length of different items. The list of the most commonly used tools for measuring length is given below:

• Ruler
• Tapes
• Yardsticks
• Meter sticks
• Feet/foot scale

Meter is also called the SI unit of length or base unit of length.

Given: lengths of two bodies are i1 = (20 ± 0.5)cm & i2 = (15  ± 0.2)cm

Now, sum of the two length & difference of these lengths we need to find.

i1 ± i2 = (20 ± 0.5)cm ± (15  ± 0.2)

i1 ± i2 = (20 + 15)cm ±  (0.5 + 0.2)cm

i1 ± i2 = (35 ± 0.2)cm

Thus, sum = 35 + 0.2 = 37 cm

difference = 35 - 0.2 = 34.3cm