IGCSE Mathematics Paper-1: Specimen Questions with Answers 158 - 158 of 324

Question 158

Describe in Detail

Essay▾

Solve

(a) (i) Write the above expression with each number rounded to two significant figure.

(ii) Use answer to find an estimate for the value of the expression.

(b) Find value of the original expression. Give your answer correct to 2 decimal places.

Explanation

Here,

(a) Here, expression is .

Now, by rounding each number to two significant figures:

  • So, 6.86 will be 6.9 because after 8 there is 6 which is greater than 5, so 8 will be rounded and be 9.
  • 1.17 will be 1.2 because after 1 there is 7 which is greater than 5, so 1 will be rounded and be 2.
  • 2.59 will be 2.6 because after 5 there is 9 which is greater than 5, so 5 will be rounded and be 6.
  • 3.73 will be 3.7 because after 7 there is 3 which is less than 5, so 7 will remain as it is.

So, expression will be like: .

(b) Here, answered expression after changing to two significant figures is:

  • So, it will be like:
  • So, as per BODMAS (Brackets, Order (Exponent) , Division, multiplication, Addition, Subtraction) first of all we have to remove brackets and in brackets there are to calculations from which multiplication will take place first:
  • Now, in brackets subtraction will be:
  • At last, division will be:

(c) Here, original expression is: .

  • So, it will be like:
  • So, as per BODMAS (Brackets, Order (Exponent) , Division, multiplication, Addition, Subtraction) first of all we have to remove brackets and in brackets there are to calculations from which multiplication will take place first:
  • Now, in brackets subtraction will be:
  • At last, division will be:

Now, correct it to two decimal places we will get: because there is 8 after digit 2, which is greater than 5, so 2 will be rounded and be 3.

Note: two decimal places means two digits after decimal point.

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