# IGCSE Mathematics Paper-1: Specimen Questions with Answers 78 - 80 of 175

## Question number: 78

Short Answer Question▾

### Write in Short

Solve the equation

### Explanation

Here, equation is

## Question number: 79

Short Answer Question▾

### Write in Short

AB is a chord of a circle, O is center. Angle OAB = . Calculate angle AOB.

### Explanation

Here,

As we can see in the figure AB is chord and O is center, so OA and OB will be radius of the circle.

So, these radiuses will make same angle with points of chord.

So, Angle OAB = , so angle OBA =

Now, in any triangle addition of all angles will give

So, in

.

## Question number: 80

Essay Question▾

### Describe in Detail

The population of India was 1.252 billion in 2013. It is expected that this population will increase by 30 % by the year 2015. Calculate the expected population in 2015.

### Explanation

Here, Population is. (1 billion = 1000 million)

Expected population will increase by 30%.

So, increment in population will: .

So, expected population in 2015 will be

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