# NCERT Class 7 Solutions: Integers (Chapter 1) Exercise 1.1 – Part 2

Q-4 A plane is flying at the height of 5000 m above the sea level. At a particular point, it is exactly above a submarine floating 1200 m below the sea level. What is the vertical distance between them?

Solution:

• Height of plane above the sea level

• Floating a submarine below the sea level

• ∴The vertical distance between the plane and the submarine

• Thus, the vertical distance between the plane and the submarine is 6200 m.

Q-5 Mohan deposits Rs. 2,000 in his bank account and withdraws Rs. 1,642 from it, the next day. If withdrawal of amount from the account is represented by a negative integer, then how will you represent the amount deposited? Find the balance in Mohan’s accounts after the withdrawal?

Solution:

• Withdrawal amount is represented as negative integer

• Thus, the balance in Mohan’s account after withdrawal is Rs. 358.

Q-6 Rita goes 20 km towards east from a point A to the point B. From B, she moves 30 km towards west along the same road. If the distance towards east is represented by a positive integer then, how will you represent the distance travelled towards west? By which integer will you represent her final position from A?

Solution:

Let Rita move on a number line with point A as zero.

• According to the number line, Rita moves towards east is represented by a positive integer. In this case point B would be 20 (20 km).

• Later she moves in opposite direction means Rita moves west, this will be represented by negative integer -30 (30 km).

Distance from A to B

Distance from B to C

Distance from A to C

Thus, Rita is at final position from A to C is -10 km.

Q-7 In a magic square each row, column and diagonal have the same sum. Check which of the following is a magic square.

Solution:

Understand that the sum of a positive number and a negative number results in subtraction operation.

1. 1st magical square

• Taking Rows

• Taking 1st row

• Taking 2nd row

• Taking 3rd row

• Taking Columns

• Taking 1st column

• Taking 2nd column

• Taking 3rd column

• Taking diagonals

• Taking 1st diagonal

• Taking 2nd diagonal

This box is not a magic square because all the sums are not equal.

2. 2nd t magical square

• Taking Rows

• Taking 1st row

• Taking 2nd row

• Taking 3rd row

• Taking Columns

• Taking 1st column

• Taking 2nd column

• Taking 3rd column

• Taking diagonals

• Taking 1st diagonal

• Taking 2nd diagonal

This box is a magic square because all the sums are equal.