Flashcards · J560 · Topic 4

Approximation and estimation flashcards

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Significant figures: which zeros count?: Zeros before the first non-zero digit of a decimal are place holders and do not count. Zeros between other digits count. Keep final zeros: 0.0070463 to 2 s.f. is 0.0070.
How do you estimate a calculation?: Round each number to 1 significant figure (use the nearest perfect square for a root), work out the simpler calculation, and write the answer with ≈. Show the rounded numbers.
Error interval: x = 2400 to 2 significant figures: The unit of rounding is 100; half of it is 50. 2350 ≤ x < 2450
Error interval: x = 0.58 truncated to 2 decimal places: Lower limit is the value; upper limit is one whole unit more: 0.58 ≤ x < 0.59
Bounds of a calculation: which bounds give the maximum?Higher: Add: UB + UB. Subtract: UB − LB. Multiply: UB × UB. Divide: UB ÷ LB. (For the minimum, swap every UB and LB.)
Error interval for a count: 200 cars to the nearest hundredHigher: A count is discrete, so the largest possible value is a whole number: 150 ≤ n ≤ 249 (or 150 ≤ n < 250). For a measured 200 g it would be 150 ≤ m < 250.