Question

Three measurements are made as 18.425 cm, 7.21 cm and 5.0 cm. The addition should be written as:(A) 30.635 cm(B) 30.64 cm(C) 30.63 cm (D) 30.6 cm

Answer 1

Answer:

D

Explanation:

When two phtsical quantity are added or subtracted there should be as many decimal places retained in final result as are there in the number with least decimal place

Answer 2

answer : option (D) 30.6

explanation :

rule of significant figures in addition : first of all, add all the given numbers in normal fashion. after that round the answer to the least number of places to the decimal point of any number in the problem.

for instance, let two numbers 1.23 and 2.4 are given and we have to find addition of it .

step 1 : add in normal fashion,

1.23 + 2.4 = 3.63

now, 2.4 is the number which has only one digit after the decimal point.

so, final answer will be = 3.6 [ same as 2.4 ]

now come to the point,

here three measurements are 18.425cm, 7.21 cm and 5.0cm

sum = 18.425 + 7.21 + 5.0 = 30.635 cm

here, 5.0 cm is the term in which least (i.e.,only one) digit after the decimal point. so, we round the final answer as 30.6 cm [ just same as 5.0 cm ]

hence, option (D) is correct.