Lesson I4
I4 Numerical methods in context Quiz: AQA Maths, Unit 9
20 questions
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Lesson I4, Numerical methods in context: 20 multiple choice questions for the AQA Maths (7357), Unit 9: Numerical methods, written with Revision Ninja.
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The 20 questions
-
When a numerical answer is obtained in a context problem, what should be checked?
- Only whether it is a fraction
- Only whether it is an integer
- Nothing, if the method was followed
- Its units and whether its size is sensible for the situation
-
What should follow solving a context model numerically?
- Substitute the answer back into the model and interpret it in context
- Report the raw decimal without units
- Use only the first iteration
- Ignore all values except the largest
-
A cost model x^3 - 4x - 10 = 0 uses x in hundreds of units. Find its positive root to 2 decimal places.
- 2.70
- 2.80
- 2.85
- 2.76
-
Which interval, by change of sign, locates the positive root of x^3 - 4x - 10 = 0?
- (0, 1)
- (2, 3)
- (3, 4)
- (-3, -2)
-
A tank's inflow rate in litres per minute is 3, 5, 4 and 2 at t = 0, 2, 4 and 6 minutes. Using the trapezium rule, what is the total inflow?
- 16 litres
- 26 litres
- 23 litres
- 14 litres
-
Using Newton-Raphson on f(x) = x^2 - 5 starting at x0 = 2, what is x1?
- 2.236
- 2.25
- 2.0
- 2.5
-
A river cross-section has depths 1.2, 2.0, 2.4 and 1.6 m at 0, 5, 10 and 15 m across. Using the trapezium rule, what is the cross-sectional area?
- 14.5 m^2
- 30 m^2
- 29 m^2
- 27.5 m^2
-
Newton-Raphson is applied to x^3 - 4x - 10 = 0 starting at x0 = 3. What is x1 to 4 decimal places?
- 2.7000
- 2.7826
- 2.8000
- 3.2174
-
Car speeds are 0, 4, 9 and 12 m/s at t = 0, 1, 2 and 3 s. Using the trapezium rule, what is the distance travelled?
- 19 m
- 17 m
- 25 m
- 21 m
-
For x(n+1) = sqrt(10 - x(n)) with x0 = 2, what is x2 to 3 decimal places?
- 2.828
- 2.500
- 2.702
- 2.678
-
A model needs a positive length, but a numerical solution gives x = -0.5. What is the best response?
- Reject it as not meaningful in context, and check the model or the other roots
- Square it to make it positive
- Accept it as the length
- Round it to 0.5
-
Which interval, by change of sign, must contain a root of x^2 - 3x + 1 = 0?
- (-2, -1)
- (1, 2)
- (0, 1)
- (-1, 0)
-
A trapezium estimate with n = 2 for x^2 over [0, 2] is 3. How large is the error compared with the exact value 8/3?
- About 12.5% overestimate
- About 50% overestimate
- The estimate is exact
- About 12.5% underestimate
-
For x^3 - 4x - 10, f(2.76) is about -0.015. What does this suggest?
- The root is about -0.015
- The value 2.76 is very close to a root, since f is close to zero
- The root is exactly 10
- The root is about 5
-
For an iteration x(n+1) = g(x(n)) near a root, |g'| is greater than 1. What happens?
- The iteration converges to zero
- The iteration converges quickly
- The iteration settles at the starting value
- The iteration moves away from the root
-
Why is a trapezium estimate of distance from velocity data an approximation?
- The velocity is negative
- Distance cannot be calculated from velocity
- The velocity is known only at discrete times, so the curve is replaced by straight segments
- The trapezium rule only works for whole numbers
-
A bisection-style search for a root in a model gives a sign change between 2.76 and 2.77. What is the next step?
- Halve the interval and check the sign at the midpoint
- Accept 2.76 as the exact root
- Use the trapezium rule
- Widen the interval to (2, 3)
-
Why is a numerical method preferred to an exact solution for some context models?
- The equation may have no algebraic solution, so an approximate root is found to the required accuracy
- Numerical methods remove the need for a model
- Numerical methods are always more accurate
- Exact solutions cannot be checked
-
A model gives 12.7 rabbits, but counts must be whole numbers. What is the best interpretation?
- Discard the model entirely
- Keep 12.7 as the count
- About 13 rabbits, noting that the model is an approximation
- Round down to 12 always
-
Which is a sensible sign that an iterative method has converged in a context problem?
- The iterates keep changing widely
- The function value is exactly 1
- The first value is always correct
- Successive iterates agree to the required number of decimal places
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