A light bulb is ON. Dorjee toggles its switch 77 times. Will the bulb Class 7
mediumA light bulb is ON. Dorjee toggles its switch 77 times. Will the bulb Class 7
Question 1.
A light bulb is ON. Dorjee toggles its switch 77 times. Will the bulb be on or off? Why? Class 7
Solution:
OFF, as it has been switched odd times.
Question 2.
Liswini has a large old encyclopaedia. When she opened it, several loose pages fell out of it. She counted 50 sheets in total, each printed on both sides. Can the sum of the page numbers of the loose sheets be 6000? Why or why not? Class 7
Solution:
Yes.
Total loose pages = 2 × 50 = 100
Sum of 100 consecutive numbers
= [latex]\frac{100 \times 101}{2}[/latex] = 50 × 101 = 5050.
As 5050 is less than 6000, it is possible that the sum of page numbers of the loose sheets is 6000.
Question 3.
Here is a 2 × 3 grid. For each row and column, the parity of the sum is written in the circle; ‘e’ for even and ‘o’ for odd. Fill the 6 boxes with 3 odd numbers ('o’) and 3 even numbers (‘e’) to satisfy the parity of the row and column sums. Class 7
Solution:
