# IGCSE Mathematics Paper-1: Specimen Questions with Answers 105 - 109 of 175

## Question number: 105

### Write in Short

Write down the value of x.

### Explanation

Here,

, so here, we need same fraction in right side as left side.

So,

## Question number: 106

### Write in Short

Solve the equation

### Explanation

Here, equation is

## Question number: 107

### Write in Short

The diagram shows a regular octagon and a rectangle. Calculate the values of .

### Explanation

Here, octagon is regular.

So, we can find it’s exterior angle by using the formula , where n = number of sides.

In octagon number of sides = 8, so **exterior angle** =

So, as shown in figure, its **interior angle** .

Now, for angle :

(I) As shown in figure:

**OR**

(II) As shown in figure, total angle is , so

## Question number: 108

### Write in Short

Choose from the symbols to complete the following statements.

(a)

(b)

### Explanation

Here,

(a) First statement is

- So, and . So, .
- So,

(b) Second statement is .

- So,
- So,

## 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.