# IGCSE Mathematics Paper-1: Specimen Questions with Answers 109 - 111 of 175

## Question number: 109

### Write in Short

(a) (i) Write both numbers in the calculation above correct to one significant figure.

(ii) Use your answer above to estimate the value of the calculation.

(b) Find the value of the calculation correct to three significant figures.

### Explanation

Here,

(a) (i) Number 782 correct to one significant figure will be: because in the number after 7 there is 8 which is greater than 5 so 7 will be increased by 1 and be **8 **which is significant figure while both 0s are at left side of decimal point which are not significant.

Number 44 correct to one significant figure will be: **40, **where **4** is significant figure while 0 is at left side of decimal point which is not significant.

So,

(ii) Answer of will be **20** which is estimate value of

(b) Calculation of will be: 17.77.

Now, 17.77 correct it to three significant figures: **17.8 **where 1,7 and 8 are significant.

## Question number: 110

### Write in Short

The surface area of the Saturn is 42 700 000 000 . Write this number in standard form.

### Explanation

Here,

(a) The surface area of the Saturn is 42 700 000 000

So, standard from will be:

## Question number: 111

### Write in Short

(a) Merry changed into dollars when the rate was . How many dollars did she receive?

(b) Write 5.28769 correct to 3 significant figures.

### Explanation

Here,

(a) Merry changed into dollars when the rate was .

So,

Then

she received.

(b) 5.28769 correct to 3 significant figures means there will be total of 3 digits:

- So, we will get
**5.29**because after digit 8 there is 7 which is greater than 5, so 8 will get round up and be 9.