Question

colculate with the correct number of significant 24.97153*3.243+20.46

A. 101.4427

B. 101.443

C. 101.44

D. 101.4

E. 1.01*10^2

2. How many significant about the answer of 156.4+0.8822+21=

A. ONE

B. TWO

C. THREE

D. FOUR

E. NONE

Answer 1

24.97153*3.243+20.46

From multiplication:

24.97153*3.243 = 80.98267

Number of significant figures in 24.97... = 7

Number of significant figues in 3.243 = 4

Therefore, round up to 4 significan figures

80.98267 --> 80.98

Now the addition

20.46 has 4 significant numbers

80.98 has 4 significant numbers

therefore

20.46 + 80.98 = 101.44

Round to 4 significant numbers, that is

101.4

which is letter D

2)

156.4+0.8822+21

156.4 = 4 significant figures

0.8822 = 4 significant figures

21 = 2 significant figures

156.4+0.8822+21 = 178.28

Round to two 2 significant numbers

180

which has only 2 significant numebrs (1 and 8; 0 will not have significance if not followed by a ".")

Answer is B