Bunuel wrote:

The area of a square field is 24200 sq m. How long will a lady take to cross the field diagonally at the rate of 6.6 km/hr?

A. 1 minute

B. 2 minutes

C. 2 minutes 32 seconds

D. 2 minutes 40 seconds

E. 3 minutes

These numbers are a lot easier than they appear to be. Fractions help here.

1) Find the length of the square field's sides and diagonal, D, with factoring.

Look for s=root of a perfect square and, since

\(D=s\sqrt{2}\), look for

\(\sqrt{2}\)

\(s^2=A\)

\(s=\sqrt{A}=\sqrt{24,200(m^2)}\)

\(s=\sqrt{(2*12,100)m^2}=\sqrt{(2*110*110)m^2}\)

\(s=110\sqrt{2}m\)Diagonal length =

\((s\sqrt{2})m\)

\(D=(110\sqrt{2}*\sqrt{2})m=(110*2)m= 220m\)2) Convert diagonal length from

\(m\) to \(km\)

\((1,000m=1km)=>(1m=\frac{1}{1000}km)\)

\(D=(220m*\frac{1km}{1000m})=\frac{220}{1000}km=\frac{11}{50}km\)3) Convert rate to a fraction

\(6.6kmh=6\frac{3}{5}=\frac{33}{5}kmh\)4) Find time.

\(R*T=D\), and \(T=\frac{D}{R}\)

\(T=\frac{\frac{11}{50}km}{\frac{33}{5}kmh}=(\frac{11}{50}km*\frac{5}{33}kmh)=\frac{1}{30}hour\)Any fraction of an hour * 60 = # of minutes

\(T=

\frac{1}{30}hr*60\frac{min}{hr}=2\) minutes

Answer B

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