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Marty's Pizza Shop guarantees that their pizzas all have at least 75% of the surface area covered with toppings, with a crust of uniform width surrounding them. If you order their best seller – a circular pizza with a diameter of 16 inches – what is the maximum width you can expect to see for the crust?

A. 0.8 inches
B. 1.1 inches
C. 1.6 inches
D. 2.0 inches
E. 2.5 inches

Total Area = 8 * 8 * pi
Radius = 64 pi

Surface = .75 * 64 * pi = 48 pi
Radius of surface = 4 sqrt (3) ~ 6.8

Radius width = 8 - 6.8 = 1.2

Answer: B
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emmak
Marty's Pizza Shop guarantees that their pizzas all have at least 75% of the surface area covered with toppings, with a crust of uniform width surrounding them. If you order their best seller – a circular pizza with a diameter of 16 inches – what is the maximum width you can expect to see for the crust?

A. 0.8 inches
B. 1.1 inches
C. 1.6 inches
D. 2.0 inches
E. 2.5 inches

The area of 16 inches pizza is \(\pi{R^2}=8^2\pi=64\pi\).

The minimum area covered with toppings is \(\frac{3}{4}*64\pi=48\pi\) --> the radius of the toppings is \(\pi{r^2}=48\pi\) --> \(r=4\sqrt{3}\approx\) 6,9

The maximum width for the crust possible = R - r = 8 - 6.9 = 1.1 inches.

Answer: B.

\(r=4\sqrt{3}=6.9282....\).

The maximum width for the crust possible = R - r = 8 - 6.9282... = 1.0717.... inches. -----> 1,1 width would make the surface area covered with topping less than 75%

Answer: A

I know this might be picky, but shouldn't OA be A ?
Does GMAT give these possible answers where rounding errors become very important
Please fill me in case Im missing something (which I probably do)
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Bunuel
emmak
Marty's Pizza Shop guarantees that their pizzas all have at least 75% of the surface area covered with toppings, with a crust of uniform width surrounding them. If you order their best seller – a circular pizza with a diameter of 16 inches – what is the maximum width you can expect to see for the crust?

A. 0.8 inches
B. 1.1 inches
C. 1.6 inches
D. 2.0 inches
E. 2.5 inches

The area of 16 inches pizza is \(\pi{R^2}=8^2\pi=64\pi\).

The minimum area covered with toppings is \(\frac{3}{4}*64\pi=48\pi\) --> the radius of the toppings is \(\pi{r^2}=48\pi\) --> \(r=4\sqrt{3}\approx{6.9}\).

The maximum width for the crust possible = R - r = 8 - 6.9 = 1.1 inches.

Answer: B.

\(r=4\sqrt{3}\={6.9282....}\).

The maximum width for the crust possible = R - r = 8 - 6.9282... = 1.0717.... inches. -----> 1,1 width would make the surface area covered with topping less than 75%

Answer: A

I know this might be picky, but shouldn't OA be A ?

The approximate maximum is 1.1 inches.
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Bunuel

The approximate maximum is 1.1 inches.

I understand that, but the question doesn't say anything about approximations.

Is it silently implied in GMAT that you round up to the closest number, even tho it would give you the "wrong" answer?
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Bunuel

The approximate maximum is 1.1 inches.

I understand that, but the question doesn't say anything about approximations.

Is it silently implied in GMAT that you round up to the closest number, even tho it would give you the "wrong" answer?

Word "approximate" is missing there. It should be "what is the approximate maximum width you can expect to see for the crust?"
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Hi Bunuel,

I am not able to find the solution with this method.

x be the width of the surrounding

pi (8-x)^2/pi(8)^2 = 3/4

does not lead to the answer..I am not able to find whats wrong in this approach.

Please help.

Regards,
Ravi
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email2vm
Hi Bunuel,

I am not able to find the solution with this method.

x be the width of the surrounding

pi (8-x)^2/pi(8)^2 = 3/4

does not lead to the answer..I am not able to find whats wrong in this approach.

Please help.

Regards,
Ravi

There is nothing wrong with this approach.

\(\frac{\pi (8-x)^2}{\pi(8)^2} = \frac{3}{4}\) --> \((8-x)^2=48\) --> \(8-x=4\sqrt{3}=6.9\) --> \(x=8-6.9=1.1\).
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Bunuel
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Bunuel

The approximate maximum is 1.1 inches.

I understand that, but the question doesn't say anything about approximations.

Is it silently implied in GMAT that you round up to the closest number, even tho it would give you the "wrong" answer?

Word "approximate" is missing there. It should be "what is the approximate maximum width you can expect to see for the crust?"

I think the keyword here is "at least" so, if 75% calculation comes to 1.08 we have no choice but to round up and select the closest, which in this case is 1.10 and not 1.06, which will breach the requirement of "at least 75%".. Lemme know your views. Thanks.
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emmak
Marty's Pizza Shop guarantees that their pizzas all have at least 75% of the surface area covered with toppings, with a crust of uniform width surrounding them. If you order their best seller – a circular pizza with a diameter of 16 inches – what is the maximum width you can expect to see for the crust?

A. 0.8 inches
B. 1.1 inches
C. 1.6 inches
D. 2.0 inches
E. 2.5 inches

Since the diameter is 16 inches, the radius is 8 inches, and the surface area is 8^2(π) = 64π. Since the toppings covers at least 75% of the surface area, the toppings covers at least 0.75 x 64π = 48π. Therefore, the radius of the toppings’ surface area is √48 ≈ 6.9 inches. Therefore, the maximum width of the crust is approximately 8 - 6.9 = 1.1 inches.

Answer: B
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Bunuel
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Bunuel

The area of 16 inches pizza is \(\pi{R^2}=8^2\pi=64\pi\).

The minimum area covered with toppings is \(\frac{3}{4}*64\pi=48\pi\) --> the radius of the toppings is \(\pi{r^2}=48\pi\) --> \(r=4\sqrt{3}\approx{6.9}\).

The maximum width for the crust possible = R - r = 8 - 6.9 = 1.1 inches.

Answer: B.

\(r=4\sqrt{3}\={6.9282....}\).

The maximum width for the crust possible = R - r = 8 - 6.9282... = 1.0717.... inches. -----> 1,1 width would make the surface area covered with topping less than 75%

Answer: A

I know this might be picky, but shouldn't OA be A ?

The approximate maximum is 1.1 inches.


\(\pi{R^2}=8^2\pi=64\pi\)

* 3/4 = 48pi

16 - 2.2 = 13.8 / 2 = 6.9^2 = 47.61pi

making 1.1 too big.

I don't see the word "approximate" in the question. It's "missing" but this math is easily done on scratch paper.
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