# Mental Ability-Basic Arithmetic (NCO- Cyber Olympiad Class 9): Questions 32 - 37 of 49

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## Question number: 32

» Mental Ability » Basic Arithmetic

### Question

The sum of two angles of a triangles is 80° and their difference is 10°, find all the angles of the triangle.

### Choices

Choice (4) | Response | |
---|---|---|

a. | 25°, 35°, 110° | |

b. | 60°, 58°, 70° | |

c. | 45°, 45°, 90° | |

d. | 45°, 35°, 100° |

## Question number: 33

» Mental Ability » Basic Arithmetic

### Question

How much pure alcohol should be added to 400ml of a 15 % solution to make its strength 32%?

### Choices

Choice (4) | Response | |
---|---|---|

a. | 100 ml | |

b. | 95 ml | |

c. | 90 ml | |

d. | 80 ml |

## Question number: 34

» Mental Ability » Basic Arithmetic

### Question

Given , , and find the value of the following expression correct up to three places of decimal: .

### Choices

Choice (4) | Response | |
---|---|---|

a. | 3.78 | |

b. | 3.88 | |

c. | -2.88 | |

d. | -2.67 |

## Question number: 35

» Mental Ability » Basic Arithmetic

### Question

The bacteria in a culture grows by 20 % in the first hour, decreases by 10 % in the second hour and again increases by 20 % in the third hour. If at the end of the third hour the count of bacteria is 100000. The original count of bacteria in the sample is________

### Choices

Choice (4) | Response | |
---|---|---|

a. | 129300 | |

b. | 129000 | |

c. | 129900 | |

d. | 129600 |

## Question number: 36

» Mental Ability » Basic Arithmetic

### Question

Sterling gold is 92.5 % pure gold. How many grams of sterling gold must be mixed to a 90 % gold alloy to obtain a 500 gm of a 91 % gold alloy?

### Choices

Choice (4) | Response | |
---|---|---|

a. | 100 gm | |

b. | 50 gm | |

c. | 150 gm | |

d. | 200 gm |

## Question number: 37

» Mental Ability » Basic Arithmetic

### Question

Given , , and find the value of the following expression correct up to three places of decimal: .

### Choices

Choice (4) | Response | |
---|---|---|

a. | -17 | |

b. | -12 | |

c. | -10 | |

d. | -30 |