The radius of a sphere-shaped balloon increases at a rate of 2 centimeters (cm) per second. If the surface area of the completely inflated balloon is 784π cm2, how long will it take for the balloon to fully inflate?Use SA=4πr2.

Use the surface area formula: 4πr² = 784π. Dividing by 4π gives r² = 196, so the fully inflated balloon has a radius of 14 cm. The radius grows at 2 cm per second, so reaching 14 cm takes 14 ÷ 2 = 7 seconds. The correct choice is 7 seconds.

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