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The diameter of a spherical bob, when measured with a vernier calliper, yielded the following values: 3.33 cm, 3.32 cm, 3.34 cm, 3.33 cm and 3.32 cm. The mean diameter to appropriate significant figures is:

Asked in NEET 2023 Manipur · Significant figures and rounding

• (1) 3.328 cm
• (2) 3.3 cm
• (3) 3.33 cm
• (4) 3.32 cm

Step-by-step solution

Why the other options are wrong

• (1) comes from the raw mean, carrying a fourth figure the calliper cannot resolve; each reading is good only to 0.01 cm
• (2) comes from rounding to two significant figures, one fewer than the readings themselves carry
• (4) comes from truncating 3.328 at the second decimal instead of rounding it; the next digit is 8, so it rounds up

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