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  • Perplex
    IB Math AIHL
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    Approximations & Error
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    Problem Bank - Approximations & Error

    Access custom-built, exam-style problems for approximations & error. Each problem has a full solution and mark-scheme, as well as AI grading and support.

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    IB: 6
    18

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    The exact diameter of the moon is 3480km. Arjun measures the diameter of the moon to be 3500km.

    1. Determine the percentage error in Arjun's estimate.

      [2]

    Using his measurement, Arjun estimates the surface area of the moon to be A=a×10kkm2, where 1≤a<10.

    1. Find a and k.

      [2]

    Arjun uses a millimeter ruler to measure the dimensions of a postage stamp.

    <p>The diagram shows two main elements: a set of perpendicular ruler scales in the upper‐left corner and, below/right of them, an enlarged “postage stamp”–style rectangle with a scalloped perforation border and an underwater fish scene inside.</p><ol><li><p>Ruler scales<br>• A horizontal ruler bar runs left–right, marked from 0 up to 25 mm.<br>– Fine tick marks at each millimeter.<br>– Heavier ticks and numeric labels at 5 mm intervals (5 mm, 10 mm, 15 mm, 20 mm, 25 mm).<br>• A vertical ruler bar runs top–down, aligned flush with the left end of the horizontal bar, marked from 0 up to 15 mm.<br>– Fine tick marks at each millimeter.<br>– Heavier ticks and numeric labels at 5 mm and 10 mm and 15 mm.<br>• The two rulers meet at a right angle, forming an L-shaped corner.</p></li><li><p>Postage‐stamp rectangle<br>• Overall outer shape: a wide rectangle with evenly spaced semicircular notches (scallops) on all four sides, simulating perforations.<br>• Just inside the scalloped edge is a narrower rectangular border (a single line).<br>• Interior scene:<br>– Background of layered water tones and a sandy seabed along the bottom edge.<br>– One large central fish silhouette, swimming left to right.<br>– Eight smaller fish silhouettes scattered around the large fish, at varying heights.<br>– Two clusters of wavy seaweed plants rooted on the sandy bottom—one cluster on the left, one on the right.<br>– A few small circular bubbles or dots in the water area.<br>– Transverse lighter wave shapes near the top of the water to indicate surface ripples.</p><p>- The width of the stamp is between 20 and 21mm, closer to 21.</p><p>- The height of the stamp is between 13 and 14mm, closer to 13mm.</p></li></ol>

    The height h of the stamp satisfies the inequality 13≤h<14.

    1. Write a similar inequality for the width, w, of the stamp.

      [1]
    problem image
    1. Using Arjun's measurements, estimate the minimum number of stamps necessary to cover the moon.

      [4]
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    The rate of heat production of bears is proportional to the cube of its height, measured from foot to shoulder.

    1. A black bear with height 70cm produces heat at a rate of 250W.

      1. Find an expression for the rate of energy consumption of a bear in terms of its shoulder height, h, in meters.

        [3]
      2. Hence find the rate of heat production of a 120cm brown bear. Give your answer to the nearest 100W.

        [2]

    In the arctic, the rate of heat loss, in Watts, is given by 800h2.

    1. Find the minimum shoulder height for a polar bear to survive the arctic cold.

      [2]
    20

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    21

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    22

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