IGCSE Mathematics Paper1: Specimen Questions with Answers 15  16 of 175
Question number: 15
Describe in Detail
Solve 0.4928
(a) In standard form,
(b) Correct to 2 significant figures,
(c) Correct to 3 decimal places
Explanation
Here, number is 0.4928
(a) For making standard form of 0.4928 we need to shift the decimal point left to right one times which will give: .
(b) We need to correct 0.4928 to 2 significant figures (all nonzero digits are called as significant figures) which can be: because here after digit 9 there is 2 which is not greater than 5, so 1 will remain same.
(C) We need to correct 0.4928 to 3 decimal places which can be: in which we have to consider three numbers after decimal point and the second number will be round up on the basis of third number.
Here, it means if third number is 5 or more than 5 which is 8 here so second number will get roundup and be 3 from 2.
Question number: 16
Describe in Detail
The table above gives the lengths of the rivers, correct to 2 significant figures.
Rivers  Length () 
Nile 

Amazon 

Yangtze 

Yellow River 

(a) List the rivers in order of length, largest to smallest.
________ > ________ > Yangtze > ________.
(b) Use a whole number to complete the statement in the answer space.
The length of Amazon is approximately ________ times the length of Yellow River.
Explanation
Here, correct the lengths of the rivers to 2 significant figures:
 Length of Nile will be: 6,900 km because after second significant digit 8 there is 5, so 8 will be rounded and be 9.
 Length of Amazon will be: 7,000 km because after second significant digit 9 there is 9 which is greater than 5, so 69 will be rounded and be 70.
 Length of Yangtze will be: 6,300 km which has already 2 significant figures.
 Length of Yellow River will be: 5,500 km because after second significant digit 4 there is 6 which is greater than 5, so 4 will be rounded and be 5.
(a) Here, list of rivers as per largest to smallest lengths as below:
Amazon > Nile > Yangtze > Yellow River
Because
(b) Here, length of Amazon by using whole number is:
Length of Yellow River by using whole number is:
So, the length of Amazon is approximately 1.2 times the length of Yellow River.
(Calculation: )