# IGCSE Mathematics Paper-1: Specimen Questions with Answers 68 - 71 of 175

## Question number: 68

### Describe in Detail

A ramp from a parking to a shopping mall slopes upward at an angle of to the horizontal. The length of the slope is 15 meters. Find difference in height h between the parking and the shopping mall. Give answer in meters.

### Explanation

Here, as given angle A is , AC = 15 m and we need to find length of BC which is difference of the height of mall and parking.

So, by using formula:

## Question number: 69

### Write in Short

Make the subject of the formula:

### Explanation

Here, formula is

So,

## Question number: 70

### Write in Short

(a) Find the value of y when .

(b) Make r the subject of the formula.

### Explanation

Here, equation is where,

(a)

(b)

## Question number: 71

### Write in Short

(a) The surface area of the earth is . Write this number to 3 significant digits.

(b) 72.2 % of the surface area of the earth is water. Calculate the area of water.

### Explanation

Here,

(a) The surface area of the earth is

- So, correct it to 3 significant digits we will get: because after 0 there is 1 which is less than 5, so 0 will remain same.

(b) 72.2 % of the surface area of the earth is water.

So, here surface area 100 %= 510 million

Then 72.2 %=?

So, surface area of water on earth which is sphere = .

So, for **area of water on earth is**: