AP State Syllabus AP Board 7th Class Maths Solutions Chapter 1 Integers Ex 7 Textbook Questions and Answers.

## AP State Syllabus 7th Class Maths Solutions 1st Lesson Integers Exercise 7

Question 1.

In a class test containing 15 questions, 4 marks are given for every correct answer and (-2) marks are given for every incorrect answer. (i) I3harathi attempts all questions but only 9 answers are correct. What is her total score’? (ii) One of her friends Hema answers only 5 questions correct. What will be her total score?

Solution:

i) Bharathi’s score = 4 × Number of correct answers + (-2) × Number of wrong answers

=4 × 9 + (-2) × 6 = 36 + (-12) = 24

ii) Hema’s score = 4 × (5) + (-2) × 10 = 20 + (-20) = 0

Question 2.

A cement company earns a profit of ₹ 9 per bag of white cement sold and a loss of ₹ 5 per bag of grey cement sold.

(i) The company sells 7000 bags of white cement and 6000 bags of grey cement in a month. What is its profit or loss?

(ii) What is the number of white cement bags it must sell to have neither profit nor loss, ifthe number of grey bags sold is 5400.

Solution:

i) Profit on 7000 white cement bags = 9 × 7000 = ₹ 63,000

Loss on 6000 grey cement bags = 5 × 6000 = ₹ 30,000

Net profit or loss = 63,000 – 30,000 = ₹ 33,000 profit

ii) When there is no loss then

Profit on white cement bags = loss on grey cement bags

Loss on grey cement bags = 5 × 5400 = ₹ 27,000

∴ Number of white cement bags = \(\frac{27,000}{9}\) = 3,000

Question 3.

The temperature at 12 noon was 10°C above zero. ¡fit decreases at the rate of 2°C per hour until midnight. at what time would the temperature be 8°C below zero? What would be the temperature at midnight’?

Solution:

The temperature at 12 noon = 10°C

Given temperature = 8°C below zero = – 8°C

Difference between the temperature = 10 – (- 8°) = 18°C

∴ Time lasted = 18 + 2 = 9 hours

i.e., at 9 o’ clock the temperature would be – 8C

At mid-night the temperature 10 + 12(-2) = 10 + (- 24) = – 14°C

Question 4.

In a class test (+3) marks are given for every correct answer and (-2) marks are given for every incorrect answer and no marks for not attempting any question.

(i) Radhika scored 20 marks. if she has got 12 correct answers, how many questions has she attempted incorrectly?

(ii) Mohini scores (-5) marks in this test, though she has got 7 correct answers.

How many questions has she attempted incorrectly?

Solution:

i) Let the no. of incorrect answers = x

So score = 3 × No. of correct answers + (-2) No. of incorrect answers

Radhika score = 20 marks

⇒ 20 = 3 × 12 + (-2) x ⇒ 20 = 36 – 2x ⇒ 2x = 36 – 20 ⇒ x = 16/2 = 8

∴ No. of incorrect questions = 8

ii) Mohini scores = -5

Marks for correct answers = 7 × 3 = 21

Marks for incorrect answers = -5-21 = -26

∴ Number of incorrect answers = -26 ÷ 2 = -13

Question 5.

An elevator descends into a mine shaft at the rate of 6 meters per minute. If the decent starts from 10 rn above the ground level, how long will it take to reach -350 m.

Solution:

Total length to be descend = -350 – 10 = -360 m

Rate of the speed of the elevator 6m per minute

Total time to descend = \(\frac{360}{6}\) = 60 minutes = 1 hour