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- Question
How many times in a day, are the hands of a clock in straight line but opposite in direction?
Options- A. 20
- B. 22
- C. 24
- D. 48
- Correct Answer
- 22
ExplanationThe hands of a clock point in opposite directions (in the same straight line) 11 times in every 12 hours. (Because between 5 and 7 they point in opposite directions at 6 o'clcok only).So, in a day, the hands point in the opposite directions 22 times.
Clock problems
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- 1. How much does a watch lose per day, if its hands coincide every 64 minutes?
Options- A.
32 8 min. 11 - B.
36 5 min. 11 - C. 90 min.
- D. 96 min. Discuss
Correct Answer:32 8 min. 11
Explanation:
55 min. spaces are covered in 60 min.60 min. spaces are covered in ❨ 60 x 60 ❩min. = 65 5 min. 55 11 Loss in 64 min. = ❨ 65 5 - 64 ❩ = 16 min. 11 11 Loss in 24 hrs = ❨ 16 x 1 x 24 x 60 ❩min. = 32 8 min. 11 64 11 - 2. At what time between 9 and 10 o'clock will the hands of a watch be together?
Options- A. 45 min. past 9
- B. 50 min. past 9
- C.
49 1 min. past 9 11 - D.
48 2 min. past 9 11
Discuss
Correct Answer:49 1 min. past 9 11
Explanation:
To be together between 9 and 10 o'clock, the minute hand has to gain 45 min. spaces.55 min. spaces gained in 60 min.
45 min. spaces are gained in ❨ 60 x 45 ❩min or 49 1 min. 55 11 ∴ The hands are together at 49 1 min. past 9. 11 - 3. At 3:40, the hour hand and the minute hand of a clock form an angle of:
Options- A. 120°
- B. 125°
- C. 130°
- D. 135° Discuss
Correct Answer: 130°
Explanation:
Angle traced by hour hand in 12 hrs. = 360°.Angle traced by it in 11 hrs = ❨ 360 x 11 ❩ ° = 110°. 3 12 3 Angle traced by minute hand in 60 min. = 360°.
Angle traced by it in 40 min. = ❨ 360 x 40 ❩ ° = 240°. 60 ∴ Required angle (240 - 110)° = 130°.
- 4. A clock is started at noon. By 10 minutes past 5, the hour hand has turned through:
Options- A. 145°
- B. 150°
- C. 155°
- D. 160° Discuss
Correct Answer: 155°
Explanation:
Angle traced by hour hand in 12 hrs = 360°.Angle traced by hour hand in 5 hrs 10 min. i.e., 31 hrs = ❨ 360 x 31 ❩ ° = 155°. 6 12 6 - 5. The reflex angle between the hands of a clock at 10.25 is:
Options- A. 180°
- B.
192 1 ° 2 - C. 195°
- D.
197 1 ° 2
Discuss
Correct Answer:197 1 ° 2
Explanation:
Angle traced by hour hand in 125 hrs = ❨ 360 x 125 ❩ ° = 312 1 ° . 12 12 12 2 Angle traced by minute hand in 25 min = ❨ 360 x 25 ❩ ° = 150°. 60 ∴ Reflex angle = 360° - ❨ 312 1 - 150 ❩ ° = 360° - 162 1 ° = 197 1° . 2 2 2 - 6. The length of a rectangle is halved, while its breadth is tripled. What is the percentage change in area?
Options- A. 25% increase
- B. 50% increase
- C. 50% decrease
- D. 75% decrease Discuss
Correct Answer: 50% increase
Explanation:
Let original length = x and original breadth = y.Original area = xy.
New length = x . 2 New breadth = 3y.
New area = ❨ x x 3y ❩ = 3 xy. 2 2 ∴ Increase % = ❨ 1 xy x 1 x 100 ❩% = 50%. 2 xy - 7. A towel, when bleached, was found to have lost 20% of its length and 10% of its breadth. The percentage of decrease in area is:
Options- A. 10%
- B. 10.08%
- C. 20%
- D. 28% Discuss
Correct Answer: 28%
Explanation:
Let original length = x and original breadth = y.Decrease in area = xy - ❨ 80 x x 90 y ❩ 100 100 = ❨ xy - 18 xy ❩ 25 = 7 xy. 25 ∴ Decrease % = ❨ 7 xy x 1 x 100 ❩% = 28%. 25 xy - 8. The length of a rectangular plot is 20 metres more than its breadth. If the cost of fencing the plot @ 26.50 per metre is Rs. 5300, what is the length of the plot in metres?
Options- A. 40
- B. 50
- C. 120
- D. Data inadequate
- E. None of these Discuss
Correct Answer: None of these
Explanation:
Let breadth = x metres.Then, length = (x + 20) metres.
Perimeter = ❨ 5300 ❩ m = 200 m. 26.50 ∴ 2[(x + 20) + x] = 200
⟹ 2x + 20 = 100
⟹ 2x = 80
⟹ x = 40.
Hence, length = x + 20 = 60 m.
- 9. The diagonal of the floor of a rectangular closet is 7½ feet. The shorter side of the closet is 4½ feet. What is the area of the closet in square feet?
Options- A.
5 1 4 - B.
13 1 2 - C. 27
- D. 37 Discuss
Correct Answer: 27
Explanation:
Other side = ❨ 15 ❩ 2 - ❨ 9 ❩ 2 2 2 ft = 225 - 81 4 4 ft = 144 4 ft = 6 ft. ∴ Area of closet = (6 x 4.5) sq. ft = 27 sq. ft.
- 10. A rectangular field is to be fenced on three sides leaving a side of 20 feet uncovered. If the area of the field is 680 sq. feet, how many feet of fencing will be required?
Options- A. 34
- B. 40
- C. 68
- D. 88 Discuss
Correct Answer: 88
Explanation:
We have: l = 20 ft and lb = 680 sq. ft.So, b = 34 ft.
∴ Length of fencing = (l + 2b) = (20 + 68) ft = 88 ft.
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