Bunuel wrote:

In a bakery, 70% of the doughnuts are glazed. If glazed doughnuts account for 21% of all pastries in the bakery, what percent of all pastries in the bakery are doughnuts?

A. 14.7%

B. 24%

C. 28%

D. 30%

E. 35%

Use smart numbers. The 21% figure is not straightforward. Try 60 or 120. Both integers often work with unusual percentages.

# of doughnuts = \(60\)

# of glazed doughnuts = \(42\)

70 percent of 60 doughnuts are glazed

\(0.7*60=42\) glazed doughnuts

Total # of pastries

42 glazed doughnuts equal 21% of all Pastries, P

\(42=.21P\)

\(P=\frac{42}{.21}=\frac{4,200}{21}=200\) Pastries

Doughnuts are what percent of all pastries?

D = 60, P = 200

Percent: \((\frac{Part}{Whole}*100)=(\frac{D}{P}*100)\)

Percent: \((\frac{60}{200}*100)=(\frac{3}{10}*100)=(.30*100)=\)

\(30\) percent

Answer D

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