Which of the following has four significant figures?

A rectangular swimming pool has a length of 55.3 m and a width of 25 m. What is the area of the pool, rounded to the correct number of significant figures?

A physical quantity P is given by $P = \frac{{{A^3}{B^{\frac{1}{{\;2}}}}}}{{{C^{ - 4}}{D^{\frac{3}{2}}}}}.$. The quantity which brings in the maximum percentage error in P is

The measured mass and volume of a body are 23.42 g and 4.9 ${\rm{c}}{{\rm{m}}^3}$ respectively with possible error 0.01 g and 0.1 ${\rm{c}}{{\rm{m}}^3}$. The maximum error in density is nearly

According to Joule' s law of heating, heat produced $H = {I^2}Rt,$ where I is current, R is resistance and t is time. If the errors in the measurement of I,R and t are 3%, 4% and 6% respectively then error in the measurement of H is

A thin copper wire of length $l$ metre increases in length by 2% when heated through ${10^{\rm{o}}}C.$. What is the percentage increase in area when a square copper sheet of length l metre is heated through ${10^{\rm{o}}}C.$

Which of the following measurement is most precise?

A physical quantity A is related to four observables a,b,c and d as follows $\;A = \frac{{{a^2}{b^3}}}{{c\sqrt d }}$ The percentage errors of measurement in a,b,c and d are 1%, 3%, 2% and 2% respectively. What is the percentage error in the quantity A?

One side of a cubical block is measured with the help of a vernier callipers of vernier constant 0.01 cm. This side comes out to be 1.23 cm. What is the percentage error in the measurement of area?

The period of oscillation of a simple pendulum is given by $T = 2\pi \sqrt {\frac{l}{g}}$ where l is about 100 cm and is known to have 1mm accuracy. The period is about 2s. The time of 100 oscillations is measured by a stop watch of least count 0.1 s . The percentage error in g is

How many significant figures are there in 40500?