A motorboat whose speed is 15km/hr …
CBSE, JEE, NEET, CUET
Question Bank, Mock Tests, Exam Papers
NCERT Solutions, Sample Papers, Notes, Videos
Test
Related Questions
Posted by Hari Anand 7 months ago
- 0 answers
Posted by Vanshika Bhatnagar 1 year, 5 months ago
- 2 answers
Posted by Sahil Sahil 1 year, 5 months ago
- 2 answers
Posted by Lakshay Kumar 1 year, 1 month ago
- 0 answers
Posted by Kanika . 1 month, 3 weeks ago
- 1 answers
Posted by Parinith Gowda Ms 4 months, 1 week ago
- 1 answers
Posted by Parinith Gowda Ms 4 months, 1 week ago
- 0 answers
myCBSEguide
Trusted by 1 Crore+ Students
Test Generator
Create papers online. It's FREE.
CUET Mock Tests
75,000+ questions to practice only on myCBSEguide app
Sia ? 6 years, 4 months ago
Speed of motorboat in still water = 15 km/hr
Let Speed of the stream = x km/ hr
Then speed downstream = (15+x) km /hr
and speed upstream = (15-x) km /hr
According to the question
{tex}{30 \over 15+x} +{30 \over 15-x} = 4{1 \over 2}{/tex}
{tex}\implies 30 [{15 - x +15 +x \over (15+x) (15- x)}] = {9 \over 2}{/tex}
{tex}\implies {30 \times 30 \over 225 - x^2} = {9 \over 2}{/tex}
{tex}\implies {900 \over 225 - x^2} = {9 \over 2}{/tex}
{tex}\implies{/tex}- 9x2 + 2025 = 1800
{tex}\implies{/tex} - 9x2 = 1800 - 2025
{tex}\implies{/tex} 9x2 = 225
{tex}\implies{/tex} x2 = 25
{tex}\implies{/tex} {tex}x = \pm 5{/tex}
Speed of the motorboat cannot be negative. So, x = 5
Hence, speed of the stream = 5 km /hr.
0Thank You