IGCSE Mathematics Paper1: Specimen Questions with Answers 16  16 of 324
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: )